Who Gives A Fish Forums

My tank's been acting weird lately, fish are gasping at the surface. Water params are good, 0 ammonia, 0 nitrite, nitrate at 10 ppm. Temp's steady at 78F. Any ideas what's up?

Gasping at the surface usually points to low oxygen. Have you checked your filter flow? Sometimes it gets clogged and reduces surface agitation. Also, when was the last water change?

Yep, low O2's sketchy. Try cranking up the filter or adding an air stone. What's your tank size? Overstocking can mess with oxygen levels too.

Lol, my betta did this once, turned out the heater was busted and cooking him. Double-check your gear, man. Also, any new plants or decor blocking flow?

This is concerning. Low oxygen is likely, but don't rule out contaminants. Have you used any new water conditioners or treatments recently? Some can bind oxygen. A partial water change with aged water might help.

reefmate wrote: ↑Wed Jul 02, 2025 9:41 pm Gasping at the surface usually points to low oxygen. Have you checked your filter flow? Sometimes it gets clogged and reduces surface agitation. Also, when was the last water change?

Good call on the filter. OP, if it's a HOB, clean the impeller. Gunk builds up and slows flow.

Agree with oxygen issues, but also consider CO2 levels if you're running injected CO2. Too much can suffocate fish. What's your pH? A sudden drop could indicate CO2 overload.

Had this happen in my 40-gallon last year. Turned out the powerhead died. Added a backup and problem solved. Check all your equipment, OP.

Bruh, my fish did this when I overdosed Stress Coat. Maybe cut back on additives for a bit? Also, how's the surface scum? A oily film can block gas exchange.

Simple fix: point your filter output higher to ripple the surface more. Works every time for me. Also, avoid overfeeding, it decays and eats up oxygen.