What makes a good community fish
A good saltwater community fish is hardy, accepts prepared foods, stays a manageable size and is not aggressive toward other species. It also helps if the fish is widely available captive-bred, since those fish are generally used to aquarium conditions. No fish is guaranteed to be peaceful, but the following are widely recommended as starting points.
Best peaceful picks
- Ocellaris clownfish. Hardy and iconic, with a small adult size of a few inches. A pair does well in many tanks, and clownfish adapt readily to prepared foods.
- Pajama and Banggai cardinalfish. Slow-moving, generally peaceful, and often comfortable in small groups when the tank is large enough.
- Royal gramma. A purple and yellow fish that tends to claim a cave and mostly keeps to itself, though it may posture toward similar-looking fish.
- Firefish. Slender and graceful. They are peaceful but jump, so a tight-fitting lid is important.
- Yellow watchman goby. A docile bottom-dweller that often shares a burrow with a pistol shrimp. See our guide to the best goby for a reef tank.
- Midas blenny. An active, bright blenny that adds movement without usually being aggressive.
- Chalk bass. A small, peaceful basslet that tends to take prepared foods.
Most of these are also considered reef compatible; see reef safe saltwater fish for more detail.
Fish to be careful with
Some popular fish are sold as community fish but can cause problems:
- Damselfish. Hardy, but many become territorial and aggressive as they grow.
- Dottybacks. Beautiful, but many are pugnacious toward smaller fish.
- Tangs. Many are peaceful with other species but need large tanks, and several tangs in a small tank may fight.
- Hawkfish. Interesting perchers that may eat small shrimp and fish. See flame hawkfish tank size and longnose hawkfish care before adding one.
When in doubt, research each species and keep the most aggressive fish for last. Our article on compatible reef fish goes through this in more detail.
How many fish can I keep?
There is no single formula. Stocking depends on filtration, water change schedule, fish size and temperament. A cautious approach is to start with fewer, smaller fish than the maximum you think the tank can take, add them slowly and test the water as the fish load grows. A 20-gallon tank, for instance, can generally support only a small group of small, peaceful fish, while a 40-gallon tank offers more options. Tanks that are bigger give fish more room to avoid conflict.
Planning a community by tank level
Thinking about where each fish spends its time can help you avoid crowding one area:
- Bottom and sand: gobies, jawfish
- Rockwork and caves: royal gramma, blennies, dottybacks
- Mid-water: cardinalfish, firefish, chalk bass
- Open water: clownfish (often near an anemone or corner), tangs in larger tanks
Feeding a mixed community
Offer variety: quality pellets or flakes, frozen foods such as mysis shrimp, and, for herbivores, nori or algae-based foods. Feed small amounts so shy and slow fish get their share, and watch for any fish being outcompeted. Overfeeding can raise nutrient levels, so stop when fish lose interest. For more feeding basics, see saltwater fish care.
Where to buy live fish
Local fish stores allow you to see fish in person and ask about how long they have been in the store and what they are eating. Reputable online retailers that guarantee live arrival and offer captive-bred livestock are another option. Whichever you choose, look for fish that are active, have clear eyes and intact fins, show no white spots or heavy breathing, and are eating before you take them home. Plan to quarantine every new arrival.