Fish hanging out at the top

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Discuss all topics related to freshwater and planted tanks.

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Joined: Wed Oct 20, 2010 4:45 am

Fish hanging out at the top

by arya241

Almost all my fish are hanging out at the top of the tank, mostly platys and molly's, it almost looks like there gasping for air.

Completed all water tests, and the results were good. Complete water changes every couple weeks, just did one about a week ago. Use carbon, ceramic cubes and filter pads in fluval 5xfilter. I have a 75 gallon tank with 30 fish, most small platys and a couple molly's, so i don't think its overstocked.

There are 3 fairly big plants in the tank, and part of the outtake of the filter breaks the surface of the water. I have never seen this behavior in the last 5 years this tank as been going, so im not sure if its a problem with oxygen. Only the platys and mollys are hanging out at the top, the angel, rainbow, cory and raphael cat fish seem to be just fine.

I have checked the water quality and temperature multiple times, and there all perfect. Any suggestions would be appreciated.

Posts: 1306
Joined: Sat Jul 26, 2008 1:24 pm

by yasherkoach

did you perform an oxygen (liquid) test? If so, what's the reading?

Fluval FX5 External Filter at 925 gallons per hour in a 75 gallon (should be ten times, so the filtration you have is just right), so it's not the filter

mollies require one teaspoon of aquarium salt per gallon (platies like salt too but it is not required) to place the salt in after the water change...also you should change about 25-30% water each week

what is the temperature of your tank...the higher the temperature, the less oxygen in the water column

then again, I also have tank bred red platies that hang at the top of the water surface, hang at times at the filter outtakes

as I have said several times on this forum, fish need to basically behave two ways: when feeding, the fish come to eat and as long as the fish swims like a fish or the way that particular fish should swim, then all is fine

so as long as the mollies and platies are eating when you feed them and the fish are moving or really have no real concern

still like to know the temperature and if you can, give the result on the oxygen test (if not, purchase a kit (liquid) and let us know)

Fish hanging out at the top

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