How Many Fish Is Too Many in My Aquarium?
For new aquarium owners, a common oversight is the size of the aquarium in relation to how many fish you have. While it’s easy to google what size aquarium one fish needs, there is no hard and fast rule for how to handle having more than one fish in your tank. When in doubt, choose an aquarium larger than you think you’ll need.
The Rule of Thumb for Aquarium Size
The simplest rule of thumb for aquarium size is that you should have one gallon for each inch of fish length in your tank. This rule is definitely not an end-all-be-all for selecting how many fish can be together in an aquarium. Fish-specific needs should be taken into consideration when choosing an aquarium for your fish.
The one-gallon per inch rule mainly applies to smaller fish. If you want to get larger fish, like Oscars for example, you’ll want to look into their specific tank size requirements. Larger fish need much more room to move around, so the per-inch rule does not apply well. Consider the requirements of your largest fish first. you can then start adding gallons per inch based on your smaller fish.
Consider Fish Preferences
Even if a fish isn’t large, it might still have some specific requirements when it comes to tank size and dimensions. Some fish are schooling fish or group fish, which means they often do best in groups of five or more. You’ll want to do your research on your specific fish. Learn their group size requirements and utilize the gallon-per-inch rule accordingly. Many schools of fish like to group together and race around. In this case, having a long tank might be essential to keep your fish comfortable.
Another preference to keep in mind, when calculating how many fish are appropriate, is where certain fish tend to swim or rest in the tank. Bottom-dwellers, such as plecos, don’t often leave the substrate. While the gallon-per-inch rule works fine for fish that don’t have a tank section preference, it can quickly become crowded deep in your tank if you don’t take into account your fish’s depth needs. If you want to have a lot of bottom-dwellers, it’s best to get a wide tank so that they all have space to lounge.
Fish Compatibility in an Aquarium
Something that no general rule can account for is the compatibility of fish in your aquarium. Fish range from peaceful to aggressive, with lots in between. You’ll likely want fish that have some aggressive tendencies, such as angelfish or cichlids. With semi-aggressive fish, you need to ensure you allow them extra space so that they don’t have to interact with other fish as often. Keeping aggressive fish near each other is a sure way of having some negative interactions in your tank.
If you have peaceful-natured fish, this is less of an issue. Research the fish you want to keep in your aquarium and consider allocating double space for each aggressive fish when calculating how many fish to add to your tank.
Be Generous When It Comes to Tank Size
When in doubt, offer your fish more space than they theoretically need. There is hardly such a thing as a fish tank that is too large as long as you provide timid fish somewhere to hide. You’ll also want to make sure to account for decorations and the substrate whenever you are calculating the size of your aquarium since these features can replace gallons of water in your tank’s technical size.
Do your research on your fish’s needs, and then be generous when it comes to choosing the size of your tank. Having too many fish in your aquarium can cause stress in your fish as well as ammonia issues. Give your fish the best life you can by providing them ample room to thrive.
