Are My Fish Struggling To Breathe?

[BVBfreak09]

I have one Siamese fighting fish and two mollies in a 25L tank. The pet shop said they'd be fine but ever since I added the mollies they are constantly at the top of the tank and they won't come down. Are they struggling to breathe?

 

[Noahsfish]

What type of mollies? A lot of mollies need at least 30 gallons.

 

[snazy]

Ammonia, oxygen problems, etc. Do an ammonia/nitrIte test and if not 0 for any of them, do as many water changes as needed to bring them down to 0.
Since it's a betta tank, do you have any surface agitation by the filter to create oxygen. Bettas can do without because they breed air, but not mollies.
 
And mollies are not to be kept in a 25L tank too in long term

 

[Fizzy77]

I may be wrong but I think 25L is to small, is the Betta aggressive? Have you cycled your tank/tested the water/whats the temp./filtration etc..?

 

[Madjonny]

I was told I couldn't have mollies because of their big fins, and the betta would probably attack them thinking it was one of its own...

I had this problem a few weeks back I had extremely high nitrate levels and pretty much had to cycle my tank again, all because I removed the filters out to medicate...

 

[BVBfreak09]

The mollies are Dalmatian mollies, I have 1 filter and there is surface agitation, the tank was left for a week before I put any fish in, the water was tested at the pet shop and there were no elevated levels of nitrate or ammonia, the beta isn't aggressive and the temp. Is 26 degrees celsius.

 

[fluttermoth]

Have you had the water tested since you added the fish though?
 
In any case, if ever your fish don't look 'right', the first thing you should do is a big water change; and by big I mean 80 or 90%. Drain the tank right down, leaving just enough water for the fish to swim upright (don't forget to switch your heater and filter off first!) before refilling with temperature matched, dechlorinated water.
 
It would be best if you could get some decent liquid or tablet tests of your own, rather than relying on the shop. If you do get the shop to test the water for you again, get them to write down the actual numbers for you.
 
I would also concur with the other members about the mollies. They can grow to four inches, and so are not suitable inhabitants for nano tanks. In a 25l, you'd be better off with just the betta, tbh.