20 G tank overstocked? Or more?

Mollyforever

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Howdy everyone!
So I am cycling a 20g tank so that i could move my 5 shortfin mollies (1:4 male and female ratio)

Would it be a dumb idea to get a couple more smaller fish like endlers in the new tank? Or crabs?

The water parameters for the current 10G molly tank is
pH 8.2
KH 130
GH 230 ish
No nitrite and nitrate
Ammonia levels are 0-0.5
i add 2 tbsp aqarium salt
i feed them fish flakes, peas, brine shrimp (they dont like it that much..) and blanched zucchini, and sometimes krills ( they dont like it)
Temp is 82

Please tell me if i should not any more fish since mollies are live bearers and will have lots of babies but i think i will let nature take its course.. if some strong ones survive im willing to keep them in my tank 😓

I do have live plants like anubias nana, java moss and java fern!
 

Myraan

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Haha ye. In this case whether you get away with overstocking isn't the issue, as you will soon be overstocked either way. Beautiful as they are it's one of the things that put me off about livebearers.

edit: the overstocking will be gradual though, so your system will be able to catch up with bacteria and plant growth; so I wouldn't worry until too many fry start surviving.... just keep an eye on water conditions and don't slack on maintenance.
 
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Mollyforever

Mollyforever

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Haha ye. In this case whether you get away with overstocking isn't the issue, as you will soon be overstocked either way. Beautiful as they are it's one of the things that put me off about livebearers.

edit: the overstocking will be gradual though, so your system will be able to catch up with bacteria and plant growth; so I wouldn't worry until too many fry start surviving.... just keep an eye on water conditions and don't slack on maintenance.
When some fry survive…when will I have to get a bigger tank? Is there like a number?
 

Bruce Leyland-Jones

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When some fry survive…when will I have to get a bigger tank? Is there like a number?
Straight away! 😂
Seriously though, the adult fish will be tempted to eat what they can and, unless you've planted the tank appropriately, only a few might survive.
Of course, if any do survive, then your over-stocking issue arises once more. ;)
 

Myraan

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I think it will come down too what you find out your tank can biologically cope with, how fast the babies grow, what the gender mix is, whether they are stressed by overcrowding, enjoying the company of a shoal.

Perhaps someone who has had reproducing Mollies in a similar situation might have an idea.

My worry about Mollies is that I've seen video of massive individuals that would have the bioload of a large shoal of tetra just by themselves.

But.... not having kept livebearers, it may well be the case that cannabilism "helps" a lot...
 

Byron

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A couple things to keep in mind here. And the first is, that with one male and four females, you are going to have roughly speaking a batch of fry from each female every month. There is no way the adults can eat all of these, no where close, so right off you need to have a plan for dealing with the fry.

Second issue is water quality and this fish. Mollies are the most sensitive of the livebearers, highly susceptible to problems from water conditions with too many fish. And five mollies in a 20g (assuming the standard or high 20g which is 24 inches/60 cm in length) is actually overcrowding. By Shortfin Molly, presumably the species is Poecilia mexicana and this fish can attain 5+ inches (14+ cm) and given they produce a lot of waste this has an impact on water quality. And swimming space. Mollies are impacted by any form of nitrogen (ammonia, nitrite, nitrate).
 

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