One of the biggest questions our clients have when setting up a new aquarium, is an eager “When can we get fish?” It is so exciting to pick out fish and see them swimming around in their beautiful new habitat you have created for them. Of course, that’s usually the moment that we have to be the mean ones that hesitantly say, “Let’s take this slow…” We try our hardest at Underwater Wonders to make sure that your fish survival rate is 100%. Which doesn’t always happen unfortunately. One of the ways we do this, is to make sure we help our clients chose fish that are compatible and probably won’t kill each other. So we have created this list of rules that you can use to make sure you have great success. Of course, we are always here to answer questions! Keep in mind that this guide cannot predict how every fish will behave. Some fish may turn out to be more aggressive than expected.
- Size matters
The general rule of thumb, is that you should have no more than 2 inches of adult size fish for every 10 gallons of water. The key being, you are factoring the size the fish will be, not what size it is now. Generally, this rule works very well to make sure that each fish has its own space to hide, breed, and swim freely.
- Birds of a Feather… DO NOT flock together
When choosing fish for your aquarium, keep in mind that fish of similar size, color or markings should not be kept together. So it goes without saying, no two fish of the same species should be kept together with the exception of fish that school or swim in harems. This happens because when a fish sees another fish that looks the same, it thinks that it is going to steal his territory or his mate and feels the need to defend itself and its space. Examples of schooling or harem fish are Chromis, Pseudochormis, Anthias, Grammas and Basslets.
- Keep the Peace
There are several types of aggression that can be seen with fish. Predator/prey aggression, territorial aggression, mate protection, and spawn protection. With all of these different types of aggression the key is keeping an eye on your system and noticing any of these behaviors. One way to help is to introduce more docile fish into your system before any of the more aggressive fish are introduced. That way Big Bobby Angelfish doesn’t think he is the king of the tank since he’s had it to himself for a while. It may become necessary to separate fish that are getting bullied or picked on in their habitat.
- Big Fish
There are certain large predatory fish that just can’t be kept with any small fish. These fish will eat anything smaller than them and in many cases they will eat invertebrates as well. In this case, it is a good idea to have a “Fish Only” aquarium. Some examples of these fish are Triggers, Lionfish, Groupers, Hawks, Snappers, and Pufferfish.
Final Words
Once again, these are general rules for fish compatibility. Even though they should be considered, often times a profession aquarist can “trick” the fish into living peacefully. Sometimes this can be achieved with a well thought out introduction of fish or even bringing in a bigger fish to bring a bully fish down a peg or two. The Spruce has a great fish compatibility chart that can serve a great reference for finding the right fish for your system.