How To Keep Tropical Fish From Breeding

Tropical fish can breed like rabbits! While it might look like a good thing, it isn’t for many reasons. The tank can become crowded, resulting in a wide range of issues.

From putting undue stress on the fish to breed prematurely to giving them a reason to fight over space, food, and air. Indeed, a full tank isn’t a conducive place for your fish!

Read Also: How Long Can A Betta Fish Go Without Eating?

You will also be spending more time cleaning the tank and changing its filter, as well as spend more money on food and filters. More fish in the tank, more mess to clean up. (Use the right tools when cleaning up the mess, too, such as the AquaticHI 5 in 1 Multi-Function Aquarium/Fish Tank Cleaning Tool)

Fortunately, there are easy yet effective ways of preventing your tropical fish from breeding! 

Place Either Male or Female Fish

It takes a male and female to breed and so it makes sense not to put them together in one tank. You will be able to pick either a male or female fish to put in an aquarium but not both sexes.

Your choice will depend on whether a male fish or a female fish has the appearance you want. Male guppies, for example, maybe more desirable as pets because of their multiple colors in spots, stripes, or splashes than the gray-colored female guppies. 

If your tank already has male and female fish of the same species, you should separate them. You may also want to rethink getting female fish because they may already be pregnant when you bought them, thus, defeating your purpose. 

Place Different Fish Species

Fish aren’t known to interbreed (i.e., breed with another species), so it also makes sense to put different fish species in your tank. You should also consider getting solitary fish, so there’s no risk of it becoming lonely in its tank.

If you’re getting two of the same schooling species, check that they have the same gender.

Change the Tank Conditions

Fish usually need specific tank conditions to breed, said conditions of which include water temperature, pH balance, and hardness as well as light level and amount of space.

If you know these conditions, then you can change the tank conditions to make it more uncomfortable for the fish to breed.

Keep in mind that the keywords here are “uncomfortable for breeding” since you don’t want to kill the fish by giving them less-than-optimal conditions to live. 

Choose Egg-laying Fish

Live-bearing fish aren’t ideal for breeding prevention because their offspring can survive even in difficult tank conditions. Not to mention that they can survive in a wide range of tank environment.

In contrast, egg-laying fish typically require specific tank conditions for breeding purposes so much so that even a single “off” condition will cause them to skip breeding.

What are the most common live-bearing fish to avoid in a tank then? Examples include guppies, mollies, and platys.

Place a Predator Fish

We have to emphasize that placing a predator fish for population control can be tricky, if not risky. The predator fish may well eat nearly every other fish in the tank, and you’re left with an aquatic no-fish environment.

There’s also the matter of the size of the tank to consider – a large tank is usually required since predator fish are larger than their prey.


Fish as pets are, indeed, relaxing after a long day at work, but you don’t want to see them being squeezed into a small tank like sardines in a can. Give them the space they need by preventing their overpopulation.