Water Works Wonders

The most common mistake new aquarium owners make is to put fish into a new aquarium within the first couple of days after it has been set up. This often leads to the death of all or some of the fish as the tank has no way to get rid of the toxic ammonia based waste products that the fish will produce. While there are short-term ways to keep fish alive in an uncycled aquarium, the best course of action is to help the aquarium develop its own biological nitrogen cycle before adding any fish.

The most important thing to know about any aquarium is the nitrogen cycle. This continuous series of chemical reactions in your aquarium governs when it is safe to add fish, how many fish you can add, how much food to put in the aquarium, what kind of filters you need, and how often to change the water. If you get any of these wrong, you risk all of your fish dying from the accumulated poisons that will build up in the aquarium.

When you first set up your fresh water aquarium, with clean fresh water and a good filter sized appropriately for the tank, there is virtually no microbial activity in the tank. In a healthy aquarium, there will be a thriving population of microbes that are constantly working to break down the toxins released by the decomposition of organic matter or in the waste products of the fish themselves. The most harmful of these is ammonia. When establishing an aquarium, you should buy a good test kit that will let you check levels of ammonia, nitrates, and nitrites. By watching the levels of these chemicals in your water, you can determine whether your tank has an operating nitrogen cycle and whether you can safely add fish to your aquarium.

In the old days of aquarium keeping, the nitrogen cycle would be started simply by adding fish. Ammonia would build up in the tank and would provide a food source for the microbes that would convert the ammonia to nitrites. Nitrites are less harmful to fish than ammonia, but still toxic. Once a level of nitrites was built up in the tank, a new type of microbe would establish a population and begin converting the nitrites to nitrates. Nitrates are much less harmful to fish, but still need to be removed from the tank through periodic partial water changes.

It would generally take about 4 weeks, give or take a couple, for the proper levels of microbes to establish themselves in an aquarium. In the meantime, the toxins would reach very high levels and often kill the fish that had been placed in the aquarium, especially if there were several fish added before the tank had completely cycled. The second set of fish added to the tank would do better since the nitrogen cycle had been established by sacrificing the first batch of fish. Now, we know there are better and more humane ways to establish the nitrogen cycle in an aquarium.

Lack of basic knowledge about the nitrogen cycle and how to properly control the levels of harmful toxins in the aquarium is one of the most common reasons for new aquarium owners to give up and abandon the hobby altogether. Read the other articles on this website for complete information on how to establish and maintain a working nitrogen cycle in your aquarium without killing your first batch of fish. Future articles will also address preventing and curing common aquarium fish diseases, choosing the right fish for your aquarium, and many more helpful topics for both new and experienced aquarium owners.

Salt creep is a common and unsightly ailment in saltwater aquariums. Salt creep occurs as water in the tank is splashed up on surfaces. The water evaporates but leaves behind a salt deposit- an unattractive dry white crusty mark. Salt is a corrosive material and, as such, it may leave permanent marks on surfaces to which it adheres. Salt can corrode metals and etch glass over time.

The best way to deal with salt creep around your marine tank is to prevent it in the first place. Once a month, wipe down all surfaces that come into contact with water from your tank. This includes the tank lid, lights, interior exposed glass and exterior glass. In most cases, simply wiping it down with water is sufficient but if salt creep is becoming noticeable, use a 50/50 solution of vinegar and water. Do not use vinegar on the inside of the tank as it can alter the pH levels of the tank water.

Take a moment to assess the area around your tank: the walls, floor and even ceiling. Is salt water spraying on these areas? Do you see any staining or deterioration? If so, rearrange the area around the tank to protect those surfaces. If water is spilling on to the floor, protect it with a rubberized surface. Put a cardboard shield behind the tank to protect the wall if necessary.

If you already have salt creep in or on your tank, it’s important to take immediate action. Salt can permanently cloud aquarium glass and salt creep can block light from your aquarium fluorescents. The first step if you have salt creep on your aquarium glass is to remove the fish to a fresh tank. Dump the water out of the original tank and thoroughly rinse the interior with dish soap and water. Move plants and gravel to separate containers and thoroughly rinse. Rinse the gravel until the water runs clear. Fill the tank half full of lukewarm water and top up with standard white vinegar (5 or 6% concentration). Let soak for 12-24 hours. The vinegar, which is an acid, will eat away at the salt deposit. After 12 hours, wipe the tank interior with a wet cloth and determine whether the salt deposit is coming off onto the cloth. If not, let it soak longer. Once the salt can be rubbed off with a cloth, dump the vinegar water out of the tank and rinse thoroughly with clean water several times. There should be no odor of vinegar when you are through. This is extremely important as vinegar can change the pH of the tank and stress the fish into hosting disease.

Remember to protect biological filtration systems including live rock from contact with the vinegar and from drying out in order to prevent the necessity of restarting your tanks nitrogen cycle. Every marine aquarium enthusiast encounters salt creep at one time or another. Protecting against it and cleaning it up when it happens is an important part of tank maintenance.

There are many different filtration systems that you can choose for your saltwater tank including protein skimmers, canister filters, under gravel filters, and wet/dry trickle filters. Each of these types of filters performs a specific task in the tank.

Protein skimming, also known as foam fractionating, works by using air bubbles trapped in the filter to clean out tank pollutants. The nasty particles stick to the surface of the air bubbles through surface tension until they are deposited into the filter’s collection cup. Protein filters work well in saltwater tanks but the technology is not advanced enough to work with hobby freshwater tanks. Many protein skimmers hang on the side of the tank and are convenient to work with and one of the least expensive options. Protein skimming should be used in addition to other filtration for a healthy saltwater tank.

Under gravel filters work by pulling water through the filter which contains nitrifying bacteria. They work equally well in saltwater and freshwater applications. Under gravel filters require a fair amount of maintenance to keep the pathways and surfaces clean.

Canister filters can be used alone or in conjunction with other filters. Canister filters can be filled with activated charcoal or other absorbent matter to filter out both pieces of floating material in the tank and biological contaminants. A canister filter can be used as a pre-filter to take out the large particulate matter before it hits a more finely tuned filter. Canister filters can be used for saltwater tanks but are most often found in freshwater applications.

Wet/dry trickle filters work by sucking water out of the tank through a filter that removes both biological and chemical matter. The wet/dry filter requires oxygen to work and this is provided within the filter. Because of the tendency to build up nitrates over time, the wet/dry filter is not recommended for reef aquarium communities.

Many saltwater aquarium setups use more than one filter, although the wet/dry trickle filter is the most popular. The combination used must include biological, mechanical, and chemical filtering. Biological filtering renders the most dangerous by-products of the tank, ammonia and nitrite into nitrate which can safely be removed by other types of filters and by regular water changes. Mechanical filtering is simply removing the pieces of waste from the water before they break down and produce dangerous by-products. Mechanical filters are useless, however, on already-broken-down material. Chemical filters take impurities out of the water using either activated charcoal or resins. These filters become frequently saturated so they should be changed on a regular basis and new filtration material added.

Choosing your filter set up for your saltwater tank is ultimately a matter of preference and budget once you have the three types of filtration- biological, mechanical, and chemical- covered. As in any other mechanized product, look for highly-rated filters manufactured by companies that stand behind their products with satisfaction guarantees. Regardless of the type and quality of filtration used, you must perform regular partial water changes as well.

Proper lighting in a reef tank is one of the most important determinants of whether the tank succeeds or fails. If there is too much light, algae will take over the tank and throw it out of balance. Too little light will make the coral pale and suffer. There are many different light systems advertised in the market today, including both fluorescent and incandescent. Spending time upfront before you add your corals to your tank will save you great expense and grief down the road.

Many corals use the “farming” method of eating. They grow algae in their tissues to harvest as food. This is a symbiotic relationship. The algae provide the coral food and oxygen and the coral provides the algae food from its wastes. These algae thrive and multiply through the process of photosynthesis- they harvest energy from light and turn it into chemical energy which the algae can use to expel oxygen. Photosynthesis requires adequate light and reef tanks that contain these “farmer coral” need to adjust the lighting so there is enough for the symbiotic algae but not enough to allow an algae bloom to get out of control and choke the tank.

The symbiotic algae contain pigments called chlorophyll “A” and “C”, which take in blue and red light for photosynthesis. Many reef aquarium lights will appear purple because they are a combination of red and blue lights.

The intensity of lighting is important as the wrong intensity can inhibit and eventually kill the symbiotic algae. The minimum light required is called the compensation point. This is the point where the oxygen that gets produced by photosynthesis is equal to oxygen requirements of the algae. Any less and the algae cannot effectively feed from the coral’s waste products. At the other end of the spectrum is the saturation point- the point where any further increase in light does not help speed up photosynthesis. Lighting in a reef tank must be maintained between these two points to keep the algae and the coral healthy.

The least expensive lights for the reef aquarist are regular 48 inches long fluorescent lights. Generally, six of these will be required- four “daylight” tubes and 2 Actinic tubes that produce blue light. They will have to be changed out every six months or so. Even though they will still seem to be bright to your eyes, the intensity drops over time. If you leave the lights in too long, you may notice damage to your corals. Compact fluorescent lights (CFL’s) are recent additions on the aquarium supplies market. They take up less space and give more output. You may consider these for a smaller tank space. In any case, the lights should be no more than four inches above the surface of the water. There are many reasons to not use standard incandescent lamps. The most important one is that they do not produce light in the correct spectrum for the algae. They also produce substantial heat which can heat the tank to dangerous levels. The final reason not to use them is the cost. Incandescents need to be replaced more frequently than fluorescents and cost far more over the life of the bulbs.

Lighting your reef aquarium is not difficult but it can be one of the more expensive parts of your aquarium and does take some time and planning upfront to keep your coral and fish happy and healthy.

Catfish are popular both for sport fishing and as a table fish, especially in the Deep South. Channel catfish can be found in rivers, lakes and ponds across the United States. They can get as big as 40-50 pounds with the world record channel cat weighing in at 58 pounds. A catfish is so called because of its cat-like “whiskers” around its mouth. These whiskers help the fish to taste which allows it to determine what is and isn’t food in murky waters.

Catfish are increasingly farmed both commercially and by hobbyists. Building a catfish pond is relatively easy and will provide both sport and food for many years if maintained carefully. Catfish are one of the only farmed species that can thrive in ponds less than 1 acre.

The first consideration in building a catfish pond is location. If you are converting an existing pond, then this has already been determined for you. If you are building a pond from scratch, however, you will need to consider such things as access to rainfall, watershed design, and soil structure.

All ponds are subject to evaporation and water must be replenished regularly. Although you can use nearby streams or wells as a water source, most smaller ponds are refilled with rain water. This means that the pond should be located where it has full access to rain and not under an awning or other obstruction.

The design of the surrounding watershed is also important. A watershed refers to the drainage of water from the highest surrounding point to the lowest. If your pond is uphill from your house, for example, you may experience flooding when rainfall overflows the pond. The watershed design is also important if your property is surrounded by farmland. Chemical runoff and animal feces may contaminate your pond if located downhill from the fields.

Your soil structure will dictate whether or not you need to line your pond. Sandy soils will drain away your pond water without lining. You can purchase lining material from an aquatics store or your can used the rubberized roofing material used by roofers. Your pond is likely to be wider than a single sheet so you will need to glue the seams together.

When digging your pond, consider the size of the mature catfish. They need enough depth to be able to hide from predators like raccoons and cats. Your pond should be at least 36 inches deep to make the fish comfortable and to keep it from freezing solid in winter.

Once the pond has been lined, it can be filled. If using a chlorinated source of water like a municipal supply, let the chlorine dissipate naturally into the air for 48 hours before introducing the fish. Catfish should be stocked at a scale of between 300 and 500 fish per acre. An acre is 42,000 square feet so if your pond is less than this, reduce your stocking level proportionately. Keep in mind that the fish will procreate in the pond and the population will increase. There are many great books and articles on managing a catfish pond.

Catfish can be one of the easiest and cheapest (not to mention, tastiest) meats you can grow yourself. Having your own catfish pond gives you another excuse to sit in the grass with your fishing pole and your daydreams.

Listed below are a number of important factors that could lead to failure with your salt-water aquarium. Check over the list carefully and if one applies to you, you will know what went wrong.

1. Hands were placed in aquarium without rinsing. This could have introduced soap or hand oils to tank, with harmful results.
2. Fish were not introduced to the aquarium properly. If fish were not floated in a jar or plastic bag and introduced to the tank slowly they could have developed “Ick” or they could suffer from shock, especially if changed from natural to artificial water.
3. Coral was not well cured.
4. Insufficient aeration. If not enough air, fish will die, sometimes slowly. Always have strong aeration so the water circulates all over the aquarium.
5. Fish were in poor condition when purchased. This is sometimes a leading factor and if the fish are in very bad condition it may well be impossible to save them. Before you purchase a fish examine it closely and observe whether or not it is swimming contentedly about the aquarium. Also be certain it is eating. If the fish will not eat and if it stays at the bottom or top of the aquarium without swimming around, it most likely is in poor health. Also check the fine, transparent portions of the fins for signs of “Ick” or fin rot and fungus. Never buy fish if they are dashing about the aquarium erratically or are continuously rubbing themselves against the coral as they are diseased and will infect your fish, and soon die unless quickly cured. It is especially important that you observe the fish for ten or fifteen minutes at least, before you buy. Many marine fish are being treated with copper sulfate before shipment and often the solution is too strong. The fish becomes poisoned and although he may not die right away, he will usually refuse food and gradually waste away. That’s why it’s important to see him eat before you buy. Healthy fish have healthy appetites.
6. If you had your fish flown in from an out-of-town dealer there can be complications that could lead to failure, At the present time, many dealers are using artificial sea water to ship their fish, and this could be a source of trouble. The fish first are caught by the collector, who brings them in to his main base, where they are then shipped to jobbers or dealers. Quite often the jobbers are not near the ocean, so they must use artificial sea water. The fish in this case are taken from natural sea water and transferred to artificial water before they are shipped. This is all right if the fish have been gradually acclimated to the artificial water, but sometimes that is not the case. The fish are simply dumped into the man-made water and shipped on to the dealers. Then the dealers, who may have an entirely different brand of artificial water, will put the fish into their mixture. When the customer purchases the fish he may transfer them into still another brand of artificial water. The constant change from one type of water to another, each having a different pH and mineral structure can easily result in the death of the fish. Not only are synthetic sea water mixtures quite different in structure, but the fresh water this salt is mixed with to make sea water can vary tremendously from one state to another. Therefore, if it is possible, hobbyists or dealers should request that their fish be shipped in pure sea water so that they won’t have to go through so many changes of salt solution. This one factor alone results in heavy losses of salt-water fish, both to dealer and hobbyist. If a fish is caught fresh from the sea and then shipped directly to the customer in pure sea water, the customer can float the fish in this same water and add the water to his aquarium. This will lessen the shock to the fish in the transition from natural water to man-made water and also add trace elements to the aquarium water.

If you are going to use live coral in your aquarium instead of the white, bleached coral, it should not be treated, bleached, or cured in any way, which of course would kill it. It should be handled just like a live fish, and may be taken directly from the ocean and placed in the aquarium.

While en route from the ocean to your home the coral should be kept shaded and in clean sea water, with aeration if needed. When it is placed in the tank, sufficient fresh sea water should be added to insure the health and proper chemical balance of the water. Sea water varies greatly with each location; so when gathering live coral for your aquarium it is best also to bring back enough fresh sea water to fill the tank, if possible. Remove any slime from the aquarium, if any is present, after you place the corals in your tank.

The slime can easily be taken out with a fine mesh net or siphoned out with a plastic hose. Live coral should be watched closely the first few days, and if it appears to be dead and is turning white it should be promptly removed. If you are not certain that it is dead, place it in a fish bowl or other container of sea water and observe it for a few days.

Although the distribution of live coral to aquarists away from the ocean is limited, it is can shipped by air and small heads up to six inches across, complete with live tube worms, may be ordered from collectors.

A few choice pieces of coral and a shell or two, if properly selected, will give the aquarium its basic beauty. Avoid loading your aquarium with excessive coral as this may cause much trouble. Chosen wisely, it will enhance your aquarium and even without fish, the salt-water aquarium artistically decorated with beautiful coral is a magnificent thing. When properly lighted it will handsomely decorate the finest of homes. The coral should be arranged so that it will provide hiding places for the fish so that they will feel secure. Rather than crowd the tank too much with coral, a few well chosen shells will furnish a snug, safe home for your fish. One or two choice pieces of coral, with a shell or two, should be sufficient for most aquariums, depending on the size of the tank. Then it will be a simple matter to siphon out uneaten foods without disturbing the fish.

All coral, shells, etc. must be absolutely clean and sterile before placing in the aquarium. Just because an object is snow white does not mean that it is clean. Coral should be soaked in fresh water at least two or three weeks before use. Then it should be rinsed thoroughly and if completely free of decaying odor, it may be dried, preferably in the sun. Then it may be used but with discretion. If your first aquarium was a failure it was probably due to improperly cleaned coral. Coral taken directly from the sea must be cured much longer. A minimum safety time would be from one to three months or longer depending on the size and type of coral being cleaned.

The only type of shells which should be used are shallow clam shells. These are quickly cleaned and seldom cause harm. The baby giant-clam shells of the Tridacna family are ideal as they make perfect homes for the marine fish. Pushed part way into the sand, they will leave several openings for the fish to enter or escape and it will furnish them with a dark, snug home. These shells may be obtained in any size, from an inch and a half to several feet long so they will fill the needs of any type specimen.

The best coral to use is the Staghorn, Elkhorn, Lace, or Cluster coral as these types are usually available and they are easily cleaned. They come in a wide variety of sizes and shapes and will fill nearly every aquarium need. The cluster coral is white with a beautiful brown base and it makes an attractive combination. Most of the corals will be snow white, when cleaned, with the exception of the Organ Pipe coral which is brick red. This type of coral is much in demand for it gives the desired color to an otherwise all white display. It is constructed of tiny hollow “pipes” which gives it an interesting appearance . However, because of its construction, it should be used with caution. Not more than one or two pieces should be used in the aquarium and these must be soaked and washed for at least a month to be certain that ail decayed matter is removed from their interior. This type of coral is relatively soft so that it can be easily hollowed out with an ordinary table knife, to make superb homes for your salt water pets.

Lettuce coral, Brain coral, Rose coral, etc. also may be used and they are extremely beautiful and interesting. However, because of their dense structure, they are quite difficult to cure and to be safe, they should be soaked in fresh water for at least six months before use. Then they must be inspected closely for decay and if there is still a foul odor present, they must be soaked even longer. The author has cured some exquisite specimens of Brain coral for as long as two years before finally considering them safe for the aquarium. Don’t let this discourage you however. If you have a favorite piece of Lettuce or Brain coral and would like it for your aquarium, by all means cure it! You can always set up your aquarium with one or two smaller pieces while waiting for it to cure. But don’t take a chance on it and put it in your marine aquarium until it is absolutely spotless and free from odor. You may lose your entire display.

In fish as in humans it is often far easier to prevent a disease from developing than to treat an advanced illness. The most important factors contributing to disease are:

Crowding

This is not an actual cause of disease but contributes to the rapid spread of any infection. This occurs because of a number of effects, including a shortage of oxygen dissolved in the water, excess waste products, generally weakened fish, and the obvious fact that the fish are closer together in a compact area and infectious organisms have a short and easy path from one fish to the other. The hobbyist should realize how abnormal an aquarium environment is to a fish whose natural surroundings are a lake, river or stream.

Overfeeding

This contributes to disease not so much from having the fish actually gorge themselves, but because uneaten food on the bottom of the tank will rot and pollute the water. In a tank with coarse gravel the fine food particles gradually drift into the deeper layers of gravel and may also contribute to rotting the plant roots. Occasionally fish will actually overeat and may show obvious distress. This is most likely to happen if very coarse particles of dried food are fed which may swell after they are eaten and actually obstruct the fish.

Inadequate Diet

Fishes maintained only on poor quality dried foods such as wafer foods will be stunted, weakened and subject to a variety of infections.

Water Changes

Approximately ten to twenty percent of the water in a tank should be changed weekly under ideal conditions. This prevents the build-up of excess nitrogenous wastes and will help keep the entire tank in good condition. In hard water areas this routine will also prevent the build-up of excessive hardness. Rapid changes in temperature, pH, or hardness will have a weakening effect on fish. Most fish will do well at a pH of about 7 and can survive in a range from 6 to 8. A rapid change from 6 to 8, however, will bring on immediate signs of distress. Tropical aquarium fishes do well at a temperature of about 75°F. and can tolerate temperatures from 65 to 90°F. or higher if the changes are made gradually. Fishes in a large body of water can tolerate a surprisingly low temperature, probably because of the longer period of time the water takes to cool.

Small quantities of water can be added to any tank directly from the tap if the temperature is approximately that of the aquarium, without any dechlorination or aging necessary. If all of the water is to be changed or if a new aquarium is to be set up the water should be aged overnight before the fish are added. This allows the chlorine in the tap water to dissipate of its own accord and also allows excess air dissolved in the water to decrease. This process can be speeded up by using commercial anti chlorine compounds available in aquarium shops, using recommended amounts. In some parts of the country tap water may be used without aging but the hobbyist should experiment with his local water before trying this with valuable fish.

New Additions

Most hobbyists have had the unfortunate experience of introducing new fish, plants, snails, or accessories into an established tank and noticing the sudden onslaught of diseases. Ideally, new fish should be quarantined for a week or two in a separate tank while waiting for the possible development of signs of any infection the fish may be carrying. One precaution is to treat the fish for parasites even though none are apparent. This may be done by using a formalin dip (see Table of Drugs). Some hobbyists also routinely treat their quarantine tank with acriflavine or malachite green. The new plants may be decontaminated using commercial products available from aquarium supply stores. The question of snails, clams, and mussels is an open one. These animals can serve as hosts for a variety of parasites, some of which may affect aquarium fish.

Great care should be taken with materials which were not specifically intended for aquarium use such as home-made spawning mops, old porcelain ornaments, or rocks of unknown condition picked up in the field. If such items are to be used, it is safest to test them in a separate tank with inexpensive fish.

Contamination

The careful hobbyist will reserve a special net for any tank containing diseased fish, and will either sterilize it before using it on healthy fish, or destroy it. The aquarist’s hands should always be washed after handling a diseased tank.

Poisoning

Fish are very susceptible to poisoning by many insecticides which may be used around the house. These should be avoided altogether in the fish room if possible, especially if they are in the form of sprays. Fresh paint may also be a source of toxic vapor for a period of hours after application. The safest course, if a nearby room is to be painted, is to cover the tank with several layers of paper and seal it with tape round the edges. Some of the newer paints dry rapidly and are less likely to create problems.

Cleanliness And Filtration

There are two ways of setting up a large aquarium. The most natural situation is to have a large unfiltered tank which is well planted and contains only a few fish. This should require no aeration. Over the course of time a thick layer of mulm (fish waste) builds up on the bottom. This is a combination of fish waste and fragments of deteriorating plant leaves. A tank of this type has a natural appearance and should be left alone without frequent changes of the fish population. The number of fish that can be kept in this way is limited.

Most hobbyists prefer a filtered tank with a larger potential fish population and a clean bottom free of mulm. Both outside and bottom filters are equally effective in removing particulate material from the water. Bottom filters have the additional feature of supplying effective aeration as well as filtration. Subsand filters work on a different principle and draw the fine particulate matter down into the gravel where an aerobic (oxygen-loving) bacterial culture builds up and breaks down the filtered material into harmless compounds. This type of filtration is usually effective and will keep a tank crystal clear in most cases but it is not too effective in the case of large, particularly dirty fish like goldfish. The subsand filter also seems to have an inhibiting effect on plant growth. A bad feature about this filter is that once the filter is established it cannot safely be turned off. The aerobic bacteria will die and anaerobic bacteria which can live in the gravel without the constant flow of fresh oxygenated water will rapidly take over and may putrefy the water.

A similar effect can occur if antibiotics are used in a tank with a functioning subsand filter. In this case the aerobic bacteria may be killed by the antibiotic and subsequent cloudiness can occur. A thick layer of gravel must be used with a subsand filter to make the filter effective. Other tanks need a layer of gravel only thick enough to adequately root their plants. An even thinner layer of gravel can be used if the aquarium plants are grown in individual pots. This practice has an additional advantage in enabling the hobbyist to move the plants for cleaning the tank or for netting fish.

Color changes as fish approach or reach maturity are normal phenomena and are seen in many species ranging from guppies to goldfish. Occasionally adult fish will show additional color changes varying from small areas to the entire body without any other symptoms. Local areas of increased color do not necessarily indicate disease and are not adequately explained. Total body color changes can be seen in mature goldfish occasionally. Some of the author’s blue scaled goldfish have sometimes turned pure white over the course of a year or so. Other goldfish often show gradual spreading oflighter colored areas into the usual gold color.

Young goldfish normally show black fringes on their fins and tail which gradually disappear as the fish grows. The black fringes sometimes recur in mature fish and can remain for several weeks. If the fins are not actually rotting or fungused the change is probably temporary and will spontaneously revert to normal. If the change is a result of infection or injury on the fins or tail then treatment should be directed towards the cause.

Albino fish may occasionally turn up in spawnings from any species of fish and represent spontaneous mutations. They usually will breed true. Many species of fish are now available in albino varieties. Albanism occurs similarly in humans, both as an inherited characteristic and as a spontaneous mutation.

Humans also occasionally develop a condition called vitiligo which is a local depigmentation of the skin. The cause is not known and there are no other ill effects. The color change in humans is permanent.