Amar Salvi has been a nature aquarium enthusiast for over 35 years and owns his own Nature Aquarium Gallery in Navi Mumbai, India.

Fish Compatibility Is the Key in Any Aquarium

Before getting tempted to add whichever fish catches your fancy into your community tank—spare a thought for that word 'community'!

The fish have to be compatible with each other (read: co-exist peacefully). It is also important to check whether they have the same needs. For example, some fish, such as goldfish, need cold water, while most others are tropical fish, needing warm water.

Let's understand this a little better. There are literally thousands of species of freshwater fish out there—only some of these are suitable for your aquarium, and others are best kept alone (like in a single fish species tank) or in the company of similar fish (as in cichlids). Out of the fish that can live in your aquarium, some are especially suited for community tanks due to their harmonious natures.

The 'Community' in My Community Tank

I approached the tank shown above with a view to keep discus fish as the primary showpiece. The rest of the fish were chosen for their compatibility with discuses. Given that I use my planted tank as a 'grow-out' tank for the baby discuses once they are weaned away from their parents, the choice of super-compatible species was all the more critical.

I planned my tank to ensure that I have fish occupying all the levels of the aquarium, from surface feeders who will take the first bites of the food, to mid-level feeders and finally bottom-feeders who will take care of the food settling down.

• Surface Feeders: In my tank, I have zebra danios, line danios, and one Endler's guppy. With their mouths turned upwards, these fish are adept at catching insects or food that falls in the water.
• Mid-Level Feeders: I have a shoal of rummy-nose tetras, harlequin rasboras, and the discus babies that take up this space. Neons, cardinals, black neons, etc. make an excellent addition at this level.
• Bottom Feeders: Here I have some corydoras and a bristle-nosed whiptail catfish. I also have about six otocinclus who are working 24/7 cleaning off the algae from the glass and leaves. I also have a clown loach who makes a guest appearance during feeding time.

All in all a peaceful lot living in co-existence—live and let live.

Keep These Points in Mind When Checking for Compatibility

• Research before you buy. This is probably the most important thing you can do as a favor to yourself and all the fish concerned. The internet is the best source for this information. Some sites I found useful are AquariumFish.Net and Tropica (if you are into planted aquariums).
• Don't just go by what the pet store guy has to say about a fish's compatibility. Look it up yourself. Many fish are shoaling fish, best kept in schools of 10 or more. Some others, such as Siamese fighters, are loners, best kept alone. Similarly, arowanas, flowerhorns, Oscars, and other similar fish will not bother a fish of a similar size, but if that fish can fit into their mouths, they won't think twice!
• Provide enough space for each fish. Overcrowding is another cause of aggression and stress amongst tank mates. Remember that each fish is territorial in varying degrees (cichlids are the most aggressive in protecting territory), and you need to ensure you take care of this aspect. Also take special care of their needs. For example, clown loaches, blackghosts, Synodontis, etc. like to stay in driftwood, while cichlids prefer rocky structures with lots of small caves that they can lay claim to.

Some Suitable Community Fish

Questions & Answers

Question: how many fish will my 38 gallon tank hold?

Answer: That's quite a big tank you have. The number of fish or the Bio-load the aquarium can handle is a function of whether you plan to have a lot of smaller fish like Tetras or big ones like Oscars, Arowanas,etc. In case you plan to have smaller ones, this aquarium can easily support 100 + tetras or even more. Big fish tend to eat a lot, poop a lot and generally have a lot of food leftover, so in case of bigger fish, lesser the better. They will also need the space as they grow, so I would say max of 12 Oscars or 1 big Arowana with 3-5 Oscars/Piranha,etc...

Comments

Arun Kumar on September 08, 2020:

Hi I am an new aquarist in my tank I am having gold fish, mollie,guppies for additional I planning to add new fishes like Green zebra glo, platy fishes shall put all theses fishes in single tank Pls suggest and help me and also which temperature I have maintain in heater

Darin Murphy on July 07, 2020:

I am a new aquarist and have recently made a outdoor tank. This tank is uncovered and already has a small pleco. I tried a few swordtails but they jumped out within the first day: so sad. I plan on adding at least one more pleco and am looking for a few colorful options that will get along well.

Please Help!!!

SharpMindqq on October 22, 2019:

That's helpful, thank you

Dave Bane on January 28, 2018:

Are neon tetras happy with other kinds of tetras as a community?

JH on April 09, 2017:

is adding serpae tetra to a community tank ok?

Jennay on January 26, 2017:

very very very helpful!! I now know what fish to put in my community tank. Good job

Sudhir Bhandarkar on December 05, 2016:

Very insightful write-up sir. Certainly helped me in planning a community aquarium for my home. Thank you!

Prethish Kumar on August 24, 2016:

Sir, You have a gorgeous tank!! May I know what lights are you using in your tank??

Frank on August 19, 2016:

How big is the tank? I have a 45 gal that I would like angelfish as primary. How many angels would be too many, and how many other fish can I have? Is there some kind of formula/equation?

Darren on July 14, 2016:

Do your bottom feeders compete for algae to eat?

Amar Salvi (author) from India on May 13, 2016:

Thanks for the feedback,Joe

Joe on May 13, 2016:

Thank you for sharing very informative.

Amar Salvi (author) from India on February 07, 2013:

Agree. Have learnt that the hard way.

Rich from New Jersey on February 07, 2013:

neons.......can't go wrong with neons, you can go wrong with upside-down catfish that get real big and eat the neons.

mits on January 22, 2013:

Very Useful article... very well written... thanks for this.

Amar Salvi (author) from India on January 18, 2012:

@myawn ...thank you!

myawn from Florida on January 18, 2012:

nice helpful hub thank you for the list of community fish.A good guide for setting up a tank. Thanks!