Stocking Levels Are Confusing Me

Hello, and welcome to the forum.

I've put your stock into the community creator and it comes out at 100% stocked and I would definitely say the Mollies are too much for the tank. If the box says 25litres then that will be with no substrate in and full to the brim - so it's far more likely to be about 20litres of actual water.

Clear water means nothing as you can't see ammonia, nitrite or nitrate in the water, so do you have a test kit capable of testing for those, or are you relying on the shop to tell you about water quality. Unfortunately, nearly all shops give rubbish advice.

Don't worry about you plants for now.... that's for later!

Hi Crilliams 

Unfortunately, nearly all shops give rubbish advice.

This is regrettably true - they're after your £££ at the end of the day and even the better shops will tend to lean to the optimistic side of what you can have in your tank. People understandably trust the advice of the fish shop when starting out (why wouldn't you, they're the 'professionals').

As Colin says, the Mollys especially will be too large, but the Platy and quite possibly the Guppies could also be too large depending on the dimensions of your tank (most fish benefit from greater tank width than height so if your tank is something of a cube shape then this would restrict their available swimming space). It perhaps could take 6 fish if they were very small, e.g. Endlers, perhaps Celestial Pearl Danios.

I would personally look to at least either return the Mollys (or rehome them with a friend or family member if possible). Alternatively, you could always get a bigger tank! 

Stocking isn't just about how many fish will fit, it's about the behaviour of the fish, the adult size etc. Stocking calculators are not terribly good with small tanks as all they consider is the bioload of the fish, not the size or behaviour.

As the others have said, mollies get far too big for a 25 litre tank. Platies also need a bigger tank, as do guppies.

If your water is indeed very hard, male endlers would be the best choice, maybe up to half a dozen of them. No females as you don't want any fry in a 25 litre tank. Your water might be too hard for a betta, unfortunately. You can find your hardness somewhere on your water company's website, though some do hide the info in odd places.

I guess a bigger tank might be an option

It's quite common for fish keepers to want another tank (and then another, and another....) once they're up and running with their first - affectionately referred to as Multiple Tank Syndrome (MTS) on here - so you could could just view it as getting the second tank early! Although there'll be nothing wrong with your current tank provided it has suitable occupants.

It does look like your water is pretty hard - there's nothing wrong with this but it does mean you would need to look at fish which do better in hard water conditions. Ironically, the fish you have are actually suited to hard water, but aren't suited to your tank. The Endlers we've mentioned would therefore seem to be an ideal fish for your current tank if you choose to stick with it. If you haven't come across them before, they're quite similar to Guppies in certain respects but smaller 

Alternatively, if you do go down the second tank route, I notice you mentioned you have an assassin snail and some shrimp - a 25l tank should make an good snail/shrimp tank.

As for your other water parameters; 0ppm ammonia and nitrite is good (these should be 0) and whilst 40ppm nitrates is a little on the high side it is still within acceptable limits.

I quite like to panoramic wall mounted tanks - i think they are about 50 - 60 litres perhaps this would be better.

Certainly the water capacity would be better for your current fish, although probably still not ideal for the Molly (Seriously Fish recommends a 90cm x 30cm x 30cm tank for them). I haven't seen a wall mounted tank in the flesh before but you would probably need to consider the weight this would place on your wall, how easy it would be to maintain it once it's up there and also how wide/deep the tank is (front to back), e.g. even if the tank is very long, if it's only 10cm front to back then this would still limit your fish choices.

C'mon guys.... think big!