Providing a natural habitat for your fish starts with a suitable aquarium. The suitability of your aquarium relies on several factors related to the size and dimensions, both of the fish tank and the fish itself. Many fish-keepers figure that out and attempt to research the topic, only to find conflicting advice and myths.

5 common myths about aquarium size and stocking:

  1. 1″ of fish per gallon – This myth is laughable if one puts some thought into the equation. Imagine a foot long fish in a 12 gallon aquarium! The creature couldn’t even turn around. It also doesn’t apply to many smaller fish. The fancy Platy, for example, isn’t very large, but it produces a lot of waste for it’s size.
  2. The fish will grow to the size of the aquarium – This fish myth came from the poor fish that have had their growth stunted by a small aquarium. Stunted growth is also associated with illness and a shorter lifespan. Goldfish are the most common victims of this myth.
  3. Some fish like small aquariums – The Betta is the most frequent victim of this abuse. Bettas CAN live in small puddles of water because they’ve evolved the ability as a means of survival during drought. That doesn’t mean a tiny bowl is their ultimate habitat. After all, you could survive living in a closet but that doesn’t mean you should.
  4. You only need to count the number of fish – You actually need to count everything that produces waste, including shrimp and snails.
  5. It’s better to over-stock fish tanks with aggressive species – Aggression distribution involves adding a lot of aggressive fish to a tank in the hopes that no one fish will be picked on too much. Somehow that translated into over stocking for the same effect. Over-stocking an aquarium is never recommended for any reason. The problems with pollution, etc., don’t just go away because you think you have a good reason to over-stock, and the aggression distribution theory is applicable to any size tank. It’s only the number of aggressive fish in the space that is considered.

How many fish can I put in my Aquarium?

How many fish can fit in an aquarium
With so many shapes and sizes of aquariums to choose from, it’s important to research before purchasing.
Image: Juwel Trigon 190 Bow Front from Swell UK.

How many fish, shrimp or snails you can put into your tank depends on several factors. It’s important to thoroughly research each species to ensure you have considered all of their environmental requirements. If you consider these special requirements, you’ll avoid issues associated with over-stocking.

“Avoiding problems is always preferable to solving them,” writes John B. Gratzek in the book, Aquariology. “Simple preventative measures will increase your chances of maintaining a trouble-free aquarium.”

Territory requirements – Some fish species are more territorial than others. A larger, longer tank allows for more territories, which in turn allows for more fish.

Height – Tall aquariums should be more lightly stocked than the same number of gallons in a longer tank because they offer less surface area. Tall aquariums are especially suitable for “tall” fish, like freshwater Angelfish. They may also be better for fish known to jump as you can lower the waterline.

Activity – Fish that are overly active swimmers need enough space to really take off and go.

Waste production – Some aquatic pets are “messier” than others. Pleco’s are notorious waste producers no matter what size they are, for example, as are Applesnails. These messy inhabitants require more tank volume to compensate for their higher-than-average waste production.

Length – A fish should be able to easily turn around both horizontally and vertically, plus have plenty of room to exercise.

Maintenance – The smaller the tank, the more frequently you have to do partial water changes to maintain a healthy environment for your aquatic pets. A larger aquarium doesn’t only dilute pollution, but also facilitates the growth of beneficial bacteria with more surface area for it to grow on.

Plants – If you or your fish prefer live aquarium plants, you’ll need a tank that is big enough to accommodate both them and the fish.  You may also want to choose a fish tank that isn’t too deep, so the light is able to penetrate the water and reach your aquatic plants.

If your current fish tank doesn’t measure up, it’s the perfect excuse to go shopping! You shouldn’t have any trouble finding an aquarium that suits both your fish and yourself. Specialty stores like Swell UK offer a wide range of sizes and styles to choose from, along with an educated staff to help guide you.

??? What size is your largest fish tank and what kind of fish do you have in it? Please tell us in the comments below.


© All Natural Pet Care BlogContent on this website may not be used elsewhere without expressed permission. Thank you for respecting the effort that we have put into our original content.

DISCLOSURE: We may receive compensation for links to products on this website.

DISCLAIMER: Statements on this website may not have been evaluated by the FDA, Health Canada nor any other government regulator. The information and products provided by are not intended to diagnose, treat, cure, nor prevent any disease and are intended for educational purposes only. READ MORE…

COMMENTS ARE MODERATED – Legitimate comments will be published after a short delay. Spam will not be published.

3 thoughts on “How Many Fish can I put in my Aquarium?

  1. I wish people would learn these basics BEFORE THEY GET FISH! So many senseless deaths & frustration. Good job eeducating peeps.

Comments are closed.