What’s too many fish?

[Pizzafan]

Hi All,

i have a 20 long planted tank stocked with:

1 bolivian ram, 1 black lyretail molly, 2 zebra danios (I know, they prefer a school, but I really don’t want more 🙂 ), 4 Kuhli loaches and a nerite snail

I’m starting to think this thing may be close to maxing out for a comfortable bioload, but is there some extra room here for a few more? Thinking a school of neon tetras would look awesome in there at some point, or maybe one more odd-ball mid level swimmer

 

Edited June 20, 2021 by Pizzafan

[xXInkedPhoenixX]

Too many fish usually means that the tank can't handle the bioload. My 20 gallon Tall has 10 Harlequins, 3 adult mystery snails, 1 baby mystery, 2 nerites, and about 14 or so Otocinclus catfish. I have lots of plants and 2 air driven filters. My tank tests great and is stable. 

If you have a heavily planted tank with good filtration and your tank already tests well, there is potential for more. 

Edited June 20, 2021 by xXInkedPhoenixX
to clarify

[laritheloud]

On 6/19/2021 at 8:12 PM, xXInkedPhoenixX said:

Too many fish usually means that the tank can't handle the bioload. My 20 gallon Tall has 10 Harlequins, 3 adult mystery snails, 1 baby mystery, 2 nerites, and about 14 or so Otocinclus catfish. I have lots of plants and 2 air driven filters. My tank tests great and is stable. 

If you have a heavily planted tank with good filtration and your tank already tests well, there is potential for more. 

This is a really good (and really reassuring!) guideline. I worry that I have too many fish in my 29 gallon due to my tetras breeding unexpectedly, but my parameters are all great and I struggle to keep nitrates high enough for my plants. It's comforting to know that my tank is doing just fine by these metrics!

[lefty o]

two things to look at, 1 the tank becomes too crowded, and 2 it cant handle the bio load, and or you cant do enough maintenance to keep up with it. how many fish a certain size tank can handle has many variables.

[Pizzafan]

Good to hear! I’ll give this thing more time to see if it stays consistent for a while, then think about adding some more. It definitely looks like there is space for more swimmers, especially in the top half. The tank is pretty heavily planted (low light plants like Java ferns, moss, water lily), with a good number of hiding places. Also have a fluval 50 for the 20 gallon tank, so hoping that extra level of filtration helps

[tonyjuliano]

Simplified answer…

There are “too many fish” if the levels of zero ppm ammonia, zero ppm nitrite & less than fifty ppm nitrate cannot be maintained by the other organisms present in conjunction with the frequency of water changes you are willing to commit to.

[NanoNano]

Probably also good to call out that if you ever do get in an overstocked situation- you want to be deliberate and thoughtful about how you "back out of it" lest you further upset your biome.

 I recently did a "midnight tank check" and found 14 visible adult trumpet snails,  the same amount of adult Neo shrimp, and probably 2x as many juveniles of both in a 3 gallon Betta tank.  I removed half of the adult snails and shrimp (assuming that there were even more adults I wasn't seeing) and the tank cleanliness level went from pristinely clear to "freshman dorm room" in about 48 hours.  Lesson learned.

Edited June 20, 2021 by NanoNano