Tips For Stocking Your Aquarium!




Tips For Stocking Your Aquarium

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Stocking an aquarium can be quite the challenge with all the beautiful specimens in the pet store and the amount of conflicting info online. Many aquarists end up with too many fish, fish they can’t properly care for or fish that just aren’t compatible. This results in dead fish, stress-related diseases and just an overall miserable aquarium experience way too often!

To help figure out how to stock your aquarium succesfully, here are a few tips that might be worth looking into.

Make a stocking plan beforehand

This is the most important step and unfortunately also the one that is skipped the most. Before you head out to the aquarium store, plan which fish you want in your aquarium and don’t let yourself be tempted by all the colorful, exotic looking specimens on display – you may end up with fish that grow much too big for your aquarium, aggressive fish or a very sensitive species. Oscar fish, pictured above, are an example of a species that often falls victim to impulse buys.

Instead, if you’re not sure how you want to stock your aquarium or if you’re looking for the perfect match for the dream species you’re setting up the aquarium for, visit a place like the Seriously Fish Knowledge Base first. Let yourself be inspired by the photos and information there and build a stocking plan from that.

Mind the water layers

When stocking an aquarium, something to keep in mind is that different species of fish live in different water layers. For example, Corydoras catfish can almost always be found foraging on the bottom of the aquarium, while most schooling fish prefer to stick to the middle of the tank.

To make things easier, aquariums are usually divided in two (for tanks smaller than 20 gal/76 L) or three (20 gal/76 L and up) water layers. The key to a well-stocked aquarium that looks balanced is to prevent having multiple species in one water layer – otherwise things will start to look messy and it’s easy to overstock.

So before you head out to the pet store, look up some videos of the fish you like, determine in which water layer they live and keep that in mind while putting together a stocking plan.

Examples of top layer species: Marbled Hatchetfish (Carnegiella strigata), Clown Killifish (Epiplatys annulatus), Honey Gourami (Trichogaster chuna)

Examples of middle layer species: Mosquito Rasbora (Boraras brigittae), Ghost Catfish (Kryptopterus minor), Threadfin Rainbowfish (Iriatherina werneri)

Examples of bottom layer species: Corydoras, Zebra Loach (Botia striata), Rhinogobius duospilus, Cherry shrimp

Examples of fish that live in multiple water layers: Puffer fish, Otocinclus catfish

Compare information!

When choosing which fish are suitable for your aquarium, it’s imporant to look up not only how big the aquarium should be for them and in which water layer they live, but also find information about:

  • Temperament
  • Water layer
  • Optimal water values/temperature
  • Whether the fish needs to live in groups or not
  • Activity level
  • Preferences when it comes to water flow, lighting and plants
  • Preferences when it comes to substrate

This information is very important because it helps you figure out which fish are compatible and which aren’t. For example, if you know Betta splendens (pictured above) is very territorial and prefers very calm tankmates, this narrows down the choice of tankmates to species that are peaceful and not too colorful. Then, you can continue searching from that point of view and further build your stocking plan.

Ask for advice

There are plenty of great aquarium forums to be found around the internet. There are general ones, but also more specific ones that focus on a single fish species. Once you have found a forum you like, you can open a topic in the right area asking for advice on stocking your aquarium. The members often have years of experience and can help you find tankmates for your dream fish, build a stocking plan from scratch with you or review the stocking plan you made yourself and help you improve it.

This way you can benefit from other people’s experience – and don’t be shy, because most forum members love to help! Just be sure not to believe everything you read right away. Getting a second opinion is a good idea, as not all forum members know a lot about properly stocking an aquarium.


Stocking an aquarium is easier when you think as long as you do your research beforehand and take your stocking plan to the store with you.

Unfortunately there is still a lot of incorrect info out there, like the “1 inch per gallon”-rule which can only be applied to a select few species, but with a lot of research and the help of knowledgeable forum members you can figure out what works for you.

Be sure to always have a plan B, especially when working with more aggressive/territorial species. Check with your pet store whether it’s okay to bring fish back and always have a spare aquarium/tub ready to separate fish that turned out to be incompatible despite your research beforehand until you’ve found a new home for them. Happy fishkeeping!

Want to share your own aquarium stocking tips or need more help figuring out your stocking list? Don’t hesitate to leave a comment below.

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5 thoughts on “Tips For Stocking Your Aquarium!”

  1. I agree that the ‘one gallon per inch’ rule is incorrect and can be applied to a few species. A lot of websites think it is correct. The tank size depends on the fish’s size,activity level, and temperament. Great article

  2. I have set up a 52 litre tank and that. I think 6 goldfish and 2 of the sucker cat dish will go good. Can you say your thoughts? Thanks.

  3. One thing I’d add is to have a backup plan if a fish simply refuses to get along with his tankmates. Every now and then you’ll come across a fish that is, well, a jerk. Having another tank free or buying from a store that accepts returns/exchanges can be a big help when you need it.

    • That is a very good point! Those things can indeed happen when you’re working with less peaceful fish, like bettas. Some just get along great with their tankmates and some behave like total jerks. I’ll add that to the article!


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