Why Do 4 Fish Swim At The Top Of The Tank But The Rest Are Fine????

Question

Hi,

I would appreciate it if someone could help me with this as it is annoying me & I want to know what to do.

I am quite new at fishkeeping & I am being troubled by 4 of my fish.

I have a 30 litre tank with a RENA Filstar Filter & a RENA 25 watt heater. In my tank I have 4 Peppered Corys, 1 Male Betta, 1 Dalmation Molly & 3 Leopard Danios.

My Betta & my Corys seem to live in perfect happiness. The problem I have is with the Molly & the Danios. They spend all the time at the top of the tank with their mouths on the surface just swimming round & round yet when I go to the pet store the Mollys & Danios there are swimming all around the tank.

I have done a Tetra 6 in 1 test and my tank passed all the tests. I have tried water changes, siphoning the gravel & replacing the filter cartridge but they don't seem to want to come below the surface.

I thought it might be an oxygen problem but then surely it would affect my Betta and Cory's.

Please could someone offer advise.

Answer 1

If the danioses are swimming at the top that is very normal behaviour. Then ur tank is just fine.

Answer 2

What is the temperature of the water...it should be 75c that is the best temp for most fish.  Some will tolerate 80c but perhaps that's why the 4 fish are at the surface gasping because it's too warm.  If you got the temp at 80c...lower it.

Answer 3

well a bit of info about ur betta. if there was a chemical spike in ur water, ur betta is more resiliant than the others because he has the labrynth oragn which allows him to breathe at the surface. helps explain why he is not effected.

what does the TETRA 6in 1 test HAVE? i am not a fan of tetra products anymore and the stripes are not that accurate. i would use API FRESHWATER MASTER TEST KIT. way more accurate and it will test for ammonia.

now as said before with the previous answerers, they are top dwellers. HOWEVER if they are at the surface GASPING for air than there might be a chemical spike. try retesting ur water with the test kit, stated above or take it to a pet store to test it. check ALL the LEVELS- PH, NO2,NO3, and NH3/NH4.  if there is no chemical spikes then you need to increase the aireation in the tank. good luck please post additional details on ur chemistry, so i can furhter help u. HELP ME! HELP U! LOL. good luck.

Answer 4

increase water circulation,add more oxygen,check the ph and ammonia levels

Answer 5

Mollies and Danios are both surface dwellers and SHOULD be swimming along the surface.  In stores, the tanks are so small and stressful that they are forced to swim into lower levels they wouldn't naturally inhabit.  Also, your tank really isn't big enough for Danios...  These are VERY active SCHOOLING fish, so you need 5+, which there just isn't enough space for in a 30 liter tank.