Hi

A lot of my tropical fish are gasping. I recently moved them to a larger tank (190l) and I suspect that the filter isn't strong enough.

I was thinking of buying a Cosmo 3500F which has a max flow 2300 L/H, but I can't find anything on the Internet about it.

Is this a reliable brand?

Cheers

hi ive got two off the next size down running in a 100ltr tanks an they seem to be fine

If the fish are gasping at the surface it wont be the filter it will be a lack of oxygen at higher temps, try airating the water or move the filter outlet closer to the surface to increase surface disruption which will add more oxygen to the water.