When you purchase a fish for your aquarium, there is no 100% sure-fire way of knowing whether the specimen you’re buying is healthy or not. If there was, there would be no need for fish guarantees! Professional aquarists spend years learning how to recognize if fish are healthy. Fish that appear healthy may have internal problems that are not yet visible. The fish may be genetically weak (which by the way, there’s nothing you can do about), or in the case of marine fish, there are many species which just don’t do well in captivity. There are however, ways to make a well educated guess. There are many things one can look for to determine if a fish is healthy. Many aquarium stores will not assist you in determining whether a fish is healthy or not. After all, they do want to sell the fish! Here’s a list of tips to follow when you’re buying a fish.

Fins should be erect, especially the dorsal (top fin) - Collapsed fins usually spell trouble. Please note: there are exceptions! Puffers curl their caudal fin (tail) up against their body. Butterfly fish only erect their dorsal fins when alarmed. This is normal. If in doubt, call us! We’ll be happy to give you advice at any time.

The fish should interact with one another as they pass each other, moving out of the way when a more dominant fish approaches. Fish that allow themselves to be bullied are not feeling well.

All the fins should be intact. If a fin has a small nip out of it, but the fish acts normally, this may be OK, but avoid a fish with torn or ripped fins.

Respiration should be normal. Compare the gill movement of a fish with other fish in the tank. Although fish with higher metabolic rates respire (breathe) a little faster, all of the fish in a tank will usually move their gills at roughly the same rate. Extremely rapid gill movement indicates stress.

Darker or patchy coloration is a good indicator of stress. Before you buy a fish, try to know what it should look like under normal conditions. Get a good fish book.

As a fish swims toward you or away from you, look carefully at its body on edge for raised bumps or tiny raised growths. As a fish swims past you, look at its fins and on its body for tiny white crystals that look like salt or tiny black nodules that look like "blackheads" (these are parasite infestations). A fish with cauliflower-like growths on the edge of its fins has Lymphocystis (a virus), and is stressed If many fish in a store exhibit these conditions, I would not buy fish from that store.

If a fish bullies or snaps at all of the fish in an aquarium at the fish store, it probably will do the same in your tank! Ask if a fish is abnormally aggressive when buying it. Don’t buy into the claim that an aggressive fish will settle down because it’s the new fish in the tank. While this is true in some cases, sometimes this only lasts until the "new fish" gets comfortable. Then it’s PARTY TIME! 

In saltwater, DO NOT BUY: Undulated or Queen Triggers, Sohal Tangs, or Passer Angels, unless you want a very aggressive tank. In freshwater, avoid Manguenese and Dovii Cichlids. The only cure for their aggression is a sharp blow with a hammer, and they’ll probably attack the hammer! If you have a peaceful freshwater community tank, avoid most Barbs, Serpae Tetras, and most Cichlids.

Unless you have at least a marine 300-gallon aquarium . . . PLEASE! Do not buy a shark!

Unless you have a 100 gallon or larger aquarium, it is not a good idea to buy saltwater fish that grow larger than six to eight inches in captivity (with the exception of some moray eels). This includes certain groupers and snappers. Exceptions to this rule are slow-moving fish such as Lionfish in saltwater or Oscars in freshwater.

Shop for fish often, but without always buying. You can get a better feel for the overall health of the livestock in a store (as well as the knowledge of the staff) that way. If you are interested in a fish that isn’t eating today, it may be eating and well acclimate to captivity in a day or two.

Test the knowledge of employees at a particular store. If they don’t appear to know the livestock they sell, they may not be taking good care of it. Ask a few "stupid" questions that you already know the answers to. "Will this six-inch Lionfish go well in my aquarium community with my Royal Gramma?" or "I have a fifty-five gallon aquarium. Will this Leopard Shark work in my tank?" or "I have a freshwater plant tank. Can I put these African Cichlids or those Silver Dollars in my aquarium?" You may be surprised at some of the answers you’ll get. By the way, the answer to all three of those questions is NO! (Without exception). If an aquarium store employee doesn’t know the answer to a question, they should say so, and find someone who does know the answer. Guesswork can kill fish.

Spend some time watching the fish you’re interested in buying. Sometimes you’ll see things you didn’t notice right away because your eye was captured by the bright colors of a particular specimen. Look past the beauty of a fish at its skin and fins. Then watch how it behaves for a while.

Raise your hand in front of the tank, and casually rest it on or just above the top of the aquarium (Don’t let an employee see you do this; they may think you’re going to "tap on the glass"). Watch the fish as you do this. The fish that rush to the surface to be fed, have been in captivity the longest. Even new fish that are still shy, should be alert enough to at least look up at your hand, or swim for cover. Fish that show no interest at all are either very new and still dazed from their journey, or unhealthy. Please Note: There are some fish, such as new Lionfish, who will not react to this test. These fish instinctively remain motionless if they feel threatened.

Ask an employee if they have just fed the fish in the tank you’re looking at. If the answer is yes, wait a while before asking to see your prospective fish fed. If the answer is no, ask if they will feed the fish a prepared dry or frozen food, not live food. Marine fish that aren’t 100% healthy, or that may have been caught with drugs or cyanide will often snap at moving food out of an instinctual urge (Please note: Some fish only eat live food. There are exceptions to every rule.). When you’re watching a fish eat in a store, stand back from the tank so the fish do not feel intimidated by your presence. If a fish does not immediately attack the food, give it a few minutes to notice the food. If it still doesn’t eat, it is either new, or not feeling well. We recommend only buying fish that eat very well, no matter how beautiful or desirable the fish is.

Sometimes it is not a good idea to shop for fish in a store that’s having a really busy day. Besides the fact that you may not get good service, employees are more likely to make mistakes if they’re under pressure to get to other customers who’ve been waiting a while. A tank of fish may have been fed several times in an hour for several customers, and the fish are full! This means that a healthy fish may not eat (an excellent test of fish health). The fish are stressed by all the people who’ve passed by, and looked in on them. Tanks are getting "tapped on" by ignorant people who want to see the fish "jump." Fish may have been caught out of the tank you’re looking at just a few minutes ago, so all of the fish in that tank could be very stressed.

Check fish prices! If a fish is being sold at a bargain price, and the store isn’t running a sale, the fish probably isn’t a bargain at all! Cyanide and drug caught fish will always be cheaper (and die sooner) than hand-caught fish. A diver who uses drugs to catch fish can catch more per hour, so the cost of the fish is far less. The health of an unusually inexpensive specimen should always be questioned.

A fish SHOULD ALWAYS be caught with two nets. Using one net will usually only result in a mad chase around the tank trying to catch an animal that is very adept at avoiding capture. The exception to this is the great fish catcher, who can snag a fish with one swoop off the surface. A fish that has been caught after a long chase will be extremely stressed. Don’t let it happen to the fish that you want to buy. It should be OK to politely suggest using two nets. If it isn’t, reconsider shopping in that store.

| Read Other Articles |

Back to Top