20 Gallon Aquarium Stocking


New Member
Reaction score
Hello! We have a fairly new tank, and it has cycled. It is 20 gallons, and we've been adding a few fish a week to it. So far, we have 4 platies, 2 mollies, a candy stripe pleco, a mystery snail, and 6 neon tetras. According to Aqadvisor, that comes to 82% stocked. I'm getting a better filter, and after I do, my kids would like one more fish. They've had their eyes on a Dwarf Gourami. But, I've read a lot about disease with these fish and it has me nervous. Any other suggestions for an eye catching fish that would work in our community tank? Or are the Dwarf Gourami problems not as bad as they sound? Thank you so much!!


Well Known Member
Reaction score
South Texas
1 year
Welcome to the fishlore forum.

The Aqadvisor site is a good tool to get a very basic picture of stocking, but it's far from reliable.

I plugged in everything about my 20g into that site one time, I think it advised my tank was about to implode.

If you get another filter, may I suggest running it side-by-side with the current one.

That way you dont lose your cycle all at once.

We bought our first tank this time last year, and it was also a 20g. It's running with 2x hang on back (HOB's) filters and a sponge filter driven by an airpump.

It is stocked with a lot more than yours and I am able to keep the ammonia and nitrites at 0 ppm and the nitrates very manageable with substrate vacs and water changes every 7-10 days.

Here is a link for a thread on the forum for effective and inexpensive ways to use DIY filter media to increase both mechanical and biological filtration.

Even if your filter is not the same as the ones mentioned on the link, it will point you in the right direction.

I agree with @candiedragon about the honey gourami.

Another option similar to the Honey is the Thick Lipped Sunset Gourami.

I have 3 and they have been hardy and non-agressive to their tankmates in my 75g. They seem to recognize me and come up to the glass.

As far as stocking suggestions, look into kuhli loaches. They have very small bio-loads and when you group them into at least 6 and give them a few places to hide, they become very entertaining.

Mine come out all the time. When they have more than one place to hide, they get comfortable and will come out more often. They come in a striped and a black/java variety.

If you get guppy's of any variety, please get only males. They are live bearers and will start to multiply with a bunch of fry.


Valued Member
Reaction score
More than 10 years
It is too small of a tank to have 2 top dwelling territorial species.
the mollies, "what sex are the", and a dwarf gourami, are likely to become very aggressive towards each other, and it is likely to turn towards the other fish as well.

the platies, the mollies, any gourami, are all top dwelling fish, It would be too many top dwelling fish,
Aqadviser is wrong too often to trust!,
Personally, I would return the mollies. unless they are balloon mollies, they need a bigger tank.

Do you have mixed sex platies? mixed sex mollies? If you do, you will soon have a lot more fish than you know what to do with. Im sure your kids will love it when they babies show up. But be prepared to answer questrions such as "why did the moma eat her babies" and , why do we have to give away 30 of the babies?, and why are some of the babies deformed?

I would leave it as is, or return regulare mollies for ballon mollies.


Fishlore VIP
Reaction score
5 to 10 years
Honestly your tank is already a bit overstocked.
If you could rehome some fish I would do this
8 neons
2 or 3 female platies
1 candy stripe pleco
1 mystery snail
Toggle Sidebar

Follow FishLore!

Top Bottom