How to Select Your Fish

Once you know which species you want, and have found an outlet that appears to be well-run and carrying healthy stock, you can select your fish. Inspect their condition and spend some time watching them; you should know how the types you want normally look and behave so you can spot problems more easily, and use the points here as a checklist to help you.

Look at all the fish in the tank before deciding. If there are any ailing individuals, hidden among the shoal, this could potentially cause serious problems for your aquarium. A number of diseases are not just spread from fish to fish, but the harmful microbes also survive in the water. Watch the fish as they are being caught, if there any you wish to avoid. It is a good sign if the shop does not have only one net for all the fish, because this may spread disease easily from one tank to another, through contaminated water.

Start small…

It is almost impossible with most tropical fish to be sure of their age, especially if fully grown. Small species such as many livebearers may live for little more than a year, so buying them is something of a lottery. Although less impressive, it is usually better to choose young fish, because it is easier to determine their age.

With larger fish such as oscars (Astronotus ocellatus) or some catfish, like suckermouths (Hypostomus species), it may still be better to pick smaller individuals. They tend to be considerably cheaper, and more important, often settle down more easily in new surroundings. This can be especially significant with ‘character’ fish like oscars which can be taught to feed from your hand.

Furthermore, if you are hoping to breed a pair, this approach can help to prevent aggression, since neither fish will yet be ready to spawn, and the male will not start to bully the female in unfamiliar surroundings. There should then be a greater chance of their being compatible in due course.

A closer examination

Check the following points to help you avoid accidentally selecting poor or unhealthy specimens.

  • Swimming signs – Are the fish swimming normally? Any that appear to be having difficulty may be showing signs of dropsy or a swim-bladder disorder, for which there are no real cures.
  • Barbels – It may be harder to assess the health of species such as catfish, which tend to remain anchored onto a stone, but there are other indicators. Check that the barbels around the mouth are of even length and do not appear to be inflamed, which sometimes happens, particularly if the substrate is dirty. While a change of environment may well lead to an improvement in their condition, the damaged area could still be vulnerable to fungus.
  • Plumpness – The fish should appear plump, rather than thin, which could indicate a chronic disease, even piscine tuberculosis. It is obviously easier to assess this if there are several fish for comparison.
  • Eye check – Make sure that the eyes are not cloudy, and that both are present (except for blind cave fish, where no eyes are visible); occasionally, fry develop missing an eye. If one or both eyes are bulging out of there sockets, this may indicate a condition known as ‘pop eye’ or exophthalmia; do not buy such fish -they often have no realistic likelihood of recovery.

Fin condition

The condition of the fins is important, especially in species that have prominent or elaborate fins. In some cases, you may notice a few small nicks, particularly in the dorsal and caudal fins, although these usually heal in due course. Abnormally closed down or clamped fins are more worrying, indicating general ill-health.

Severe erosion around the edges of all the fins is highly suggestive of either a weakened fish, or poor water conditions. Under these circumstances, fungus may take a hold, although once the fish are transferred to a fresh set-up, where the level of potential pathogens in the water will be lower, they may well recover without giving further cause for concern.

Scale damage

Take a good look at the fish’s scales, because a damaged area here can soon become infected and will start to ulcerate. While it may be possible to treat this, it will be time-consuming and potentially costly. Raised scales, held slightly away from the body, are a sign of general illness and are often seen with other symptoms, such as a reluctance to swim. Avoid any fish like this because they are likely to be seriously ill.

Colour change

In some cases, fish may exhibit poor coloration. If all the fish in the tank are less brightly coloured that you would normally expect, it may well be that the lighting is too bright, which tends to make colours look less vivid. If just one or two individuals seem pale, however, they may be sick or being bullied by others in the group.

A pale, washed-out appearance is typically associated with many types of tetra if kept under powerful lights. In the wild, these fish tend to inhabit areas of water where the level of illumination is relatively subdued; if housed under such conditions, with cover from floating plants, their coloration will very quickly become more vibrant again.

Healthy appetite

If you want to have a final check on the condition of the fish, ask to see them feeding. A fish that is eating well will usually be quite healthy. Unfortunately, some shyer species such as certain catfish may not be ready to eat in this way. With these fish, look in the water for pieces of food such as cucumber, which show signs of having been rasped by the fish’s mouthparts – then you can be fairly sure that they are eating properly.

Filed Under: Pets & Animals


About the Author: Fred Goodson has a passion for pets and animals. He has 4 dogs and is planning to have another one. He is also a blogger who writes about pets and animals. Currently, he is living in New Jersey.

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