Saltwater Fish

More than 4,000 species of saltwater fish are thought to inhabit the world’s coral reefs. Reefs occupy less than 1% of ocean surface area, but provide the habitat for more than a quarter of all saltwater fish species.

In the home aquarium, saltwater fish add color, flash and personality to any tank. Selecting the best fish for your marine aquarium is a decision based on a couple of important factors:

Cycle your tank before adding saltwater fish

Everyone has their own opinion about what fish to add to a new saltwater fish tank. One of the biggest problems with new tanks is a phenomenon called New Tank Syndrome—essentially, new tanks are unstable and oftentimes fish added to a new tank perish quickly—because the environment is too harsh. The most important thing you can when setting up your new saltwater fish tank is to allow for the time to properly cycle the marine aquarium.

Cycling a marine aquarium is the process of establishing the biological filter. Adding saltwater fish (sometimes called starter fish) to a marine aquarium before the tank has completed cycling is one of the most common mistakes hobbyists make. The best way to cycle a marine aquarium is with the fishless cycling method.

Set up a quarantine tank to prevent the spread of parasites and disease

image by Hilary Kladke

It may seem like a hassle to set up a quarantine tank, but it is probably the most important thing you can do to ensure the long-term health and success of the saltwater fish in your aquarium. Parasites like saltwater ich and marine velvet spread rapidly in a marine aquarium and can be a nightmare to treat in a reef tank. The best medicine is prevention. The best way to prevent the problem is by setting up a quarantine tank.

Acclimate before adding fish to a marine aquarium

From the moment the saltwater fish is put in the plastic bag for the trek home to your marine aquarium, the water inside that bag begins to degrade and the temperature begins to change. Depending on the quality of the water when the fish was packed for transportation and the time it takes for the fish to reach your home, the water parameters inside the bag (temperature, pH, ammonia concentration) may be significantly different from the water in your tank. To avoid shocking (and potentially killing) your saltwater fish, you need to acclimate the fish to the new marine aquarium conditions. One of the most effective ways to acclimate saltwater fish is with the drip method.


There are a few things you should consider when feeding your saltwater fish:

Diseases of saltwater fish

Disease and parasitic infections are a major reason why aquarists can become frustrated with and leave the saltwater aquarium hobby. Infestations of marine velvet or saltwater ich can ransack the fish in a marine aquarium. Once inside your tank, eliminating parasites can be a major hassle.

Common saltwater fish diseases/parasitic infections are:

A great place to learn about what the different diseases look like is here.

If you are looking for a good book on the topic, check out Fish Disease Diagnosis and Treatment, by Edward J. Noga, it provides a very nice overview of the common (and uncommon) diseases, parasites and treatments.

Breeding saltwater fish

Neon Gobies: A popular saltwater fish-image by tiswango

Breeding saltwater fish is truly my passion. I have been fortunate enough to breed the Banggai Cardinalfish, Neon Goby and Common Clownfish—but there are countless other species that will readily breed in the marine aquarium. Breeding saltwater fish, in my experience, is similar to breeding freshwater fish. It is important to have healthy, mature broodstock (the fish you want to be the parents), and to feed them with highly nutritious foods. It’s almost like you need to ‘fatten up your fish’ to get them ready to breed. The three hardest parts about breeding are:

Feeding and caring for your larval fish is the hardest part of breeding saltwater fish. Still, when that hard work pays off and you have a tank of tiny fish, it is totally worth it.

The best online source for information about breeding saltwater fish is MOFIB, a forum of people dedicated to breeding. You will find an awesome amount of information there.

The best book you can buy about breeding is Matthew Wittenrich’s book, The Complete Illustrated Breeder’s Guide to Marine Aquarium Fishes. Matthew does a great job covering the generalities of breeding as well as specific accounts on a species by species basis.

The science of captive-breeding is continually advancing. Read about breakthroughs for four more species.

Written by Albert B. Ulrich III. Follow me on  and Twitter

Other information about saltwater fish

Here are some other interesting articles about saltwater fish that you might enjoy: