Girl with a bag with fish

How to buy aquarium fish to avoid problems

Aquarists, regardless of age, get very excited about populating their tanks with fish. It’s not surprising as it is a very intriguing process. There are many schools of thought concerning ways to populate an aquarium. You can stick to one biotope, create a multi-species aquarium, or focus on one/some larger groups of individuals of one species. A person with years of experience will take into account both the chemical composition of the water (its possible adaptation to the planned species), the level of microbiological stability, as well as many other factors. In this article, I will focus on the basics of buying aquarium fish. So how to buy aquarium fish?

First visit to a pet shop

Before buying fish, it’s worth visiting a few pet stores and taking a close look at the aquariums displayed in them. Remember that the tank in the shop is fish’s whole world. If you see a neglected tank, covered with algae or simply “dirty”, you should be suspicious. Such problems indicate unstable chemical parameters and danger that fish may be stressed. A continuous state of anxiety can significantly affect the fish’s immunity and make them more susceptible to diseases.

Child in a pet shop

Condition of fish

Each species behaves in a different way. An experienced person only needs one glance at a fish to judge if it is healthy. Remember that diseases often do not cause symptoms that are visible to everyone and you have to learn to catch small signals that may indicate poor condition of the fish. Take a close look at them before you buy. Don’t scare them by tapping on the aquarium because when threatened, every animal prepares to flee. Even sick fish straighten their fins and cluster together, which can falsify the picture of their health.

Quarantine of fish in a wholesale store

Few people realize how many species of fish are now imported. In a professional fish wholesale store, to which the retail customer has no access, you will find separate rooms for domestic and imported fish. Why? Mainly because of the diseases that imported fish can carry. For this reason, they are quarantined for several days to as long as several dozen days. Less honest sellers, however, can take fish directly from imports to buy them more cheaply without running an expensive quarantine. Therefore, it’s always good to ask the seller about their country of origin and whether they have been through such a quarantine – either at the wholesaler or at the pet store itself.

Bacterial diseases in fish

All bacterial diseases are impossible to diagnose with the naked eye. However, if you see a suspiciously concave belly, heavily reddened gills suggesting hypoxia, curled fins or uneven amounts of mucus covering the fish (thickening), abandon the purchase.

Internal and external parasites of fish

When mentioning parasites, most aquarists immediately think of Ichthyophthirius multifiliis. Ciliates are common unicellular orgasms. They live in every (sic!) aquarium. What’s interesting – they feed on bacteria, so they can be useful for the tank and they themselves are also food for fry. Unfortunately, some of them have a parasitic lifestyle. Under favorable conditions, they attach to the host organism (fish) causing white spot disease.

The second, probably the most well-known external parasite is Argulus foliaceus (“common fish louse”), which can be observed most frequently on veiltails and koi. Let’s not forget about internal parasites. Tapeworms, nematodes, and other roundworms are, despite appearances, fairly common “free riders” for aquarium fish. In addition to a concave or swollen abdomen and signs of weakness, long, dragging feces may be characteristic.

Be aware

Remember that diseases such as white spot disease do not come out of nowhere. Low water temperature (e.g., during long transport home, carrying a bag of fish on a cold day in your hand rather than under your jacket, etc.) promotes lowering of the fish’s immunity. The same applies to unfavorable water parameters in an aquarium where new fish are introduced. Something that is the norm for residents (fish can adapt to deviations in water parameters to a certain extent) can be dangerous for new fish. It is therefore advisable to check the aquarium water parameters with a quick strip test before introducing fish. Large environmental changes have a negative impact on immunity, as I wrote about in an article titled “The pH buffers in the aquarium”.

Home quarantine

You already know how to buy aquarium fish. However, what should you do once you bring them home? The best solution when buying new fish is to put them in a separate tank for observation for the first few/several days. This will allow us not only to notice possible disease symptoms, but also, in case of a significant difference between adult specimens of the species already in the aquarium and the newly purchased ones, to feed the latter. With the extra energy they have, they can more easily handle any minor scuffles that may occur in the early stages of cluster bonding.

Fish in a bag.

If you don’t have a quarantine tank, observe them carefully for the first few days after introducing them to a new tank. It is always advisable to have a disinfectant in the cabinet under the aquarium. It has a long shelf life, and we will be able to react immediately to symptoms that concern us, even on weekends when most stores are closed.

Releasing fish into the tank

You already know that it is a good idea to ask the seller about the quarantine method and the special requirements of specific fish species. You also know what to look for when buying fish. You already have a bag of fish, but how do you get them into your home aquarium?

I propose to do this in the best way possible for the fish. We remove the cover from the aquarium, open the bag with the fish, then wrap its edges to form a stiff “collar”. The bag opened in this way is placed on the surface of the aquarium water. Using a small cup, draw water from the aquarium and pour it into the fish bag. It’s best to do this gradually, pouring in a little water every few minutes to eventually mix in a 1:1 ratio. This will not only equalize the temperature in the bag, but will also average out the chemical parameters of the water. When we have mixed the water, after another several minutes we take the fish out of the bag with a net and place it in the target aquarium.

We take out the empty bag with the mixed water. Its content should be poured into the sewage system (water mixed in this way should not be poured into the aquarium in order to limit possible pathogen transfer). It’s ready! From now on we can enjoy the company of fish and observe their daily life.

You already know how to buy aquarium fish. Now you need to choose the right fish for you. For the first aquarium it is advisable to choose fish species that will not cause many problems to the aquarium beginner.

Michał Wyskiel

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