What does it mean when fish swim near/at the top of the tank as if wanting food, but not actually eating?

Question

I have a small tank, very small, maybe half a gallon, with five tetra fish and a algae-eater. they are all small. but all of them swim at the surface as if looking for food. is this normal?

Answer 1

Water changes will keep them alive short term, maybe a filter will help, but unless the tank is up around 5gals - take the fish back now. They are doomed otherwise.

What you saw is the fish struggling to find oxygen in the toxic water, it's one step away from being dead!!

btw the 'Algae Eater ' is probably a Common Pleco, it should grow to over a foot long in a few years time.  Compare that to the size of your tank.

Ian

Answer 2

In ludicrously small tanks, absolutely-- you're seeing your fish being poisoned by their own excretion.  The ammonia is burning their gills, making it almost impossible to breathe, and the stress is causing them to stop eating.  Until you get a REAL tank with a REAL filter and a REAL heater, you will continue to see your fish do this until they are REALLY dead.

EDIT: A syringe won't do anything for the ammonia levels which are poisoning your fish, nor will the oxygenate the water to any useful degree.  You'll need to do daily water changes and get a 10+ gallon tank ASAP.

EDIT 2: Frequent water changes will definitely help.  You not only need a filter, but a heater (the fish you listed are tropical), and a bigger tank.  Tetras need schools (which you have), but for them to swim as they should, they need room (a 10 gallon tank).  Most places should have whole 10 gallon kits (filter, heater, net, tank, hood, etc.) for less than $50.

Answer 3

No, they have used up all the oxygen in the water since it is overstocked. Add a bubbler right away and you should be fine. If you have a  filter remove a bit of water so the water surface can get aggitated and make some bubbles and get oxygen in your water.