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Choosing Fish for Your Saltwater Aquarium

Fish make great pets, and although they have the reputation for being more difficult to care for, saltwater fish have brilliant colors and exotic looks. And not all fish available in the store are actually meant to be kept in captivity. When choosing fish for your saltwater tank, find out all you can before making a purchase.

Know What You Want

Before you get any fish for your tank, do a little research to know what sort of aquarium environment you’d like to have, the kinds of fish that go together, and the way they behave.

Go to the pet store with an idea of what kind of fish you want instead of blindly buying anything that “looks nice.” This is especially important if you are planning to keep several species. You shouldn’t add a triggerfish until the very end, for example, because they are highly territorial and will consider your entire tank their own if you add them first. Also, make sure you know the food and water requirements of the species in which you are interested.

Plan for your fish to grow. If you buy a juvenile of a species and don’t know how large it can get, it could outgrow your tank.

If this is your first saltwater tank, stick to just fish at first. Good fish for beginning tanks are damselfish, gobies and blennies, basslets, some cardinalfish and surgeonfish. Invertebrate reef creatures such as starfish, shrimp or crabs are a little more difficult to care for in general and are better kept once you have some experience under your belt.

Know which fish are difficult to care for and stay away from them. Moorish idols, ribbon eels, polyp-eating butterflyfish, sponge-eating angelfish, parasite-eating cleaner wrasses and fish that have unique environmental needs or picky eating requirements pose problems even for professional aquarists.

At the Store

After you’ve decided on a general idea of what you want in your tank, there are a few things to look out for. Selecting healthy pets requires that you both ask the store personnel a few questions and make some observations on your own.

Don’t buy fish that the owner “just got in.” These fish are enduring the acclimation process at the store. Moving them before they’ve settled in may be one trauma too many. Try to buy a fish that has been with the dealer for at least two weeks.

Take your time looking at the fish you are considering. Is it swimming normally or does it seem inactive and sluggish? If the fish seems to have a hard time swimming, that may be a sign of a bigger problem.

Look closely at the skin, eyes and fins. The eyes of a healthy fish should be clear, not cloudy. The skin should be free of lesions or splotches of discolored areas (unless they are part of the coloration) and shouldn’t have a “fuzzy” appearance.

The fins should be intact and not frayed or torn. Although tears and frayed areas may be a result of a fight, they can also signify a looming bacterial infection.

Look for any signs of disease. Never purchase a fish that has white spots on its skin or fins, for example, which is an indication of either a coral reef disease or saltwater ich, both of which are caused by a parasite that will infect your whole tank. The last thing you want to deal with, especially as a beginning saltwater hobbyist, is having to treat your brand-new fish.

A fish may look sick because the dealer hasn’t made an effort to care for it properly, and all it may need is a good home. But this difference is difficult to recognize as a beginner, so until you have the experience to make that distinction, stick with fish that look to be in the best shape.

Ask the dealer what he feeds the fish you are thinking of purchasing and how often it gets fed. Healthy fish that have been feeding well will have normal rounded or “full” bellies. If the head looks abnormally large or if the abdominal area is very thin, it could be a sign that the fish isn’t eating normally – often the first sign of disease or mistreatment. In fact, one sign of good health is good appetite.

Whatever fish you finally do decide on, it should be fed before you take it home. This will give it a little more strength and energy – as well as a slight advantage in dealing with the move to your tank. Also ask about the water quality the fish has been living in. What temperature does the dealer have his aquarium set to? What is the salinity and pH.

Carrying Capacity

Freshwater fish by virtue of their natural environment are used to large fluctuations in water quality. Saltwater fish, however, rarely experience large water quality fluctuations in their natural environments and are therefore physiologically incapable of handling drastic changes. Saltwater aquariums cannot hold as many fish as freshwater systems of the same size.

A general and easy rule of thumb for an aquarium is calculated by the number of inches of fish per gallon of water. The general recommendation for a saltwater aquarium is about two to three inches of animal for every 10 gallons of water. A 50-gallon tank can, by this rule of thumb, accommodate 15 inches of fish while a 20-gallon tank can safely hold only about six inches of fish.

A trick in saltwater systems, however, is that the bigger the volume of the tank the more stable the water quality and the larger the carrying capacity it will have. If you have a little experience and pay careful attention to water quality, the 50-gallon tank can actually handle about 18 to 20 inches of fish, plus a few invertebrates. Judging what’s right for your aquarium is a matter of experience, so start with fewer fish than you think the tank can hold and then add them as the system stabilizes.

Do not add too many fish at one time to any system. A sudden overload of biological filters can cause a “crash” in your ecosystem. Add one or two creatures at intervals of a couple of weeks – especially important if yours is a brand-new tank – to let your bio-filter catch up.