5 Things Cat Lovers Need to Know Before Keeping Fish

This article first appeared on iCatCare here.

If you want to keep a fish tank in the house with your cat, this article will teach you what you need to know about keeping them both safe.  

In this article, you’ll learn some of the behaviours that can indicate a problem between your cat and your fish, the reasons behind them, and what you can do to keep both of your pets safe and happy in their home. 

Despite prevailing pop culture narratives, cats and fish can absolutely cohabitate peacefully in the same home. However, the fact remains that cats are predators and fish are some of their natural prey. As such, there is the possibility of conflict, which can end up harming both animals if not properly managed and prevented. Fortunately, these conflicts are easy to understand with a basic knowledge of cat and fish behaviours, and even easier to prevent with a few simple and thoughtful preventative measures.  

1. Certain types of fish will be more tempting to your cat than others. As hunters in low light conditions, often dawn and dusk, cats need to see movement more than anything else, so while their night vision is excellent, as far as we can tell, they have very limited color vision. As far as fish are concerned, this means that choosing brightly or dully coloured fish won’t make a big difference to your cat, but how they move will. Small, fast-moving fish, like guppies or goldfish; those that move in groups or shoals, like tetras; or just highly active fish like the Red Tail Shark, will be much more likely to attract a cat’s eye than slower-moving catfish, shrimp, or snails. Tanks with a high flow rate or lots of waving floated plants may also be more attractive to a cat; the sound of running water, as well as the visual movement, is likely to catch their attention

2. A blanket or cover is the easiest way to make your cat lose interest in a fish tank. As discussed above, seeing the motion of a fish tank is a large part of what attracts a cat’s attention to it. You can eliminate the temptation almost entirely by covering the tank with a cover, blanket, or dark cloth when you aren’t there to watch your cat. Just make sure the cover you use fits the tank properly and doesn’t dangle down to where your cat can reach it and play with it.

3. Your cat can harm your fish without even touching them. Fish, like humans, are highly susceptible to stress, which can in turn have severe negative consequences for their health. Humans might relieve their own stress by staring at a fish tank, but a cat staring into the tank all day will be a major source of stress for your fish. If they’re allowed to tap on the glass or sit on the lid of the tank, this will only compound the stress. You can tell your fish are stressed if they’re hiding more often, not eating, growing lethargic, swimming in strange or uncharacteristic patterns, or generally behaving in unusual or uncharacteristic ways. Chronic stress can also weaken their immune systems and make them more susceptible to potentially serious diseases such as Ich. If you notice any of these symptoms in your fish, first check your water parameters to make sure there isn’t a problem with your husbandry. If that’s not the problem, consider setting up a camera to see if your cat is bothering them when you’re not around.

4. Fish tanks can be a danger to cats if not properly set up and maintained. Fish tanks are large and heavy, especially when full of water. A falling fish tank could easily be fatal to a cat. Set up your tank on a sturdy, dedicated stand, away from other furniture your cat could use to jump onto it. Tuck away the cords for any filters, lights, or other electronics, so your cat can’t play with them and accidentally pull the tank down. Additionally, though your cat may like the running water, fish tank water is not safe for them to drink, and the tank must be covered with a lid for both your fish and your cat’s sake.

5. A happy and engaged cat is unlikely to bother a fish tank. If you can find activities to keep your cat’s mind and hunting instincts engaged, they’ll be too busy for a fish tank. This might be food puzzles, traditional cat toys, more play with their humans, or even setting them up to watch the TV or look out a window.  

It’s easy and not unexpected for cats and fish to come into conflict; it’s in their nature, and they are still animals. However, a careful owner can easily prevent these conflicts with some thoughtful planning. You can’t train the instincts out of your pets, but you can make them manageable.