I have a vacuum cleaner fish!?

Question

Why is my molly near the water surface constantly sucking in water or debris? I know the oxygen level is not low because I have 2 oxgyenator plants, plus the light is on so the plants aren't using oxygen. Furthermore, the filter and the airstone is in top notch condition. And the 3 guppies in there are happy and swimming.

The molly looks happy and healthy though. it swims down sometimes and goes up sometimes. And my water tests came out good. no2 nh3 equals zero, all that good stuff.

Answer 1

Since the fish involved is a molly, there could be a few reasons for this behavior. Mollies are surface feeding fish, so it may be looking for food.

What's the water temperature? As water warms, it holds less oxygen, but with a filter in the tank, the temperature would need to be very warm for the molly to be affected.

If the molly is newer than the guppies, or the tank itself is new (less then 2 months running), you might have a buildup of ammonia or nitrite. If the guppies have been in the tank longer, they may have adapted somewhat to the level, but a new fish would not have. It may also be more sensitive to the chemicals than are the guppies. See ammonia poisoning and nitrite poisoning in this link: http://www.fish-disease.net/diseases.htm The solution to this is a larger partial water change, of about 50% if you're unable to test your water to rule this out.

Answer 2

Could be that the temperature is a little high for the Mollie. Higher temps mean lower O2 levels. Don't count on any significant O2 from the plants,it's a "break even" bet at the best. The filter and air stone should do the trick, though.

Answer 3

My Molly does the same, they are surface dwelling fish. Mine will go to the bottom every once in a while. It's normal. And no your fishie is not dying.

Answer 4

they are just surface dwelling fish.

Answer 5

It's probably dieing....sorry.