[Gingerfrost]

I've been thinking about possibly buying some Pygmy Corydoras for my 20 Gallon fishtank. The only issue is I'm not sure the right amount, or if I shouldn't at all [fear of the tank being too small]. I don't know how it'll effect the Bio drop, and just don't wanna go out buying them without an idea if it'll harm the tank.

There is currently a Red Cherry Colony of maaaybee.. 20? I swear I see 5 more each month....
-------------------------- [I do pull out the clear, and add them to another tank.]
1 Amano Shrimp.
3-6 Guppies 3 females; 1 male... I can't seem to keep males alive, so they kinda rotate out? the females breed, the babies survive. (all babies are too young to sex/all females no health issues)
Then 5 Longfin Danios
10 Scuds?
lots of variation of snails, I love snails <3 [1 assassin snail to keep pop in check.]
-------------{breed various spotted ram-horns, orange ram-horns, round pest snails, a pearl colored pest snail in another tank}

I do have several different species of plants from 1 Amazon Spear, Hornwort, anubias, moss balls, java moss, and a couple other plants can't think name of.

Run 2 Airstones, I turn one off and on depending on if its night or not.
I do not run a filter, since I had no room to place it, and I don't mind changing out 2-6 gallons of water a week, sometimes pouring 1 gallon inbetween the week with distilled water or spring water [based on mood].

(Tank is a Year old)

forgot: I do run a heater, and feed every other day. (I will on my days off turn off the heater for a couple of hours. Maybe a day. Then keep the room temperature at about 72 or higher. mostly again out of muse. plus side I have huuge red cherries.) I never fully fill the tank, I leave about 5 inches of air space, covering the top with glass. So I guess the tank sits at about 15 gallons? worst case scenario, no large rocks or decorations. And a very small layer of carbsea and sand mix gravel.

 

[a modest aquarist]

Not a cory expert by any means, but in my experience they do really poor if your water conditions aren't optimal. Not saying no filter wouldn't work but I've found them to be pretty sensitive. Their bio-load isn't too crazy but without a filter I personally would reconsider. Also they tend to be very social and can stress when not in good numbers so without a dedicated filter I think you'd run into some problems down the road.

 

[jake21]

You might consider a sponge filter - even a small one is quite helpful and they aren't that expensive - mabye $20 - $15 for the air pump and $8 for the sponge filter.

https://www.amazon.com/SunGrow-Underwater-Aquarium-Must-Have-Aquarists/dp/B081S7RW53/

-
I'd go for 10 pygmy if a 20 long and the tank can handle the filtration. If a 20 high perhaps 6 pymgy.

 

[greenguppy]

If you are already running an air stone that means you already have a pump so all you need is a sponge filter. And as jake said they are only 5-8$ for a 20 gal.

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[Plinkploop]

You can always look at best types of sponges from the dollar store and choose one that works for you, attach it around the airstone and voila, diy sponge filter for a buck.

 

[greenguppy]

If you decide to go the diy root, make sure the sponge doesn't have any built in cleaning soap.

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[Plinkploop]

There's a few reviews posted on reddit and youtube about dollar store filter sponges that're pretty informative on the best types for different uses and which ones to avoid because of additives/ plastics.

 

[greenguppy]

"built in cleaning soaps" no no no. "additives" much better......

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[Gingerfrost]

Alrighty, Step 1: Sponge Filter. Thank you guys <3

So 10 Pygmies it is <3 maybe 8..

[Completely forgot to mention it was a 20 long x.x Sorry ]

 

[ichthyogeek]

The tank is definitely not too small. I keep a school of 10 in my 20L currently, and hardly see them due to their size and how the tank is laid out. Which reminds me I need to pick up some blackworms and stuff next week for them...

Honestly, if any fish "fits" the inch per gallon "rule" (it's not a rule, you shouldn't follow it), it'd probably be the pygmy corydoras. If I wasn't already planning on keeping other schools of small fish, I'd 100% do like a school of 20-30 in my 20L.

That being said, I am somewhat of an overstocker who gets away with it because he 1) does his water changes, and 2) has way too many plants in the tank to absorb all of the nutrients available.