lack of oxygen?

Question
My fish are all gasping for air at top of tank.  I do not know what size takn i have in water volume, it is approx 30 inches long and is approx 11 inches wide although the front of the tank is not flat, it is rounded. It is about 14 inches deep.  I have 4 bumblebee gobies, 10 penguins, 2 gourmais,5 black widdows, 5 cardinals, 1 sucker catfish, and 2 angel fish.

I think they are distressed, as they are almost all going to the top for air. this has been happening for approx 2 days now.

The gourmais are a new addition, and i do not know what their behaviour should be like, but they seem to be futtering around a lot, they almost look like they are trying to get out of the front of the tank.

I have very little knowledge of tropical fish, and am fairly new to keeping them.  We have had our set up for about 3 months.  We have only lost one fish, this was a black angel fish a month ago.  He was being picked on by a larger angel fish which we took back to the shop in the end as he was going after everything, and distressing lots of the other fish.

In addition the penguins seem to be hovering up the top all the time, and look like they are trying to breathe.

Its making me upset. i don't want to lose any or all of my fish.

I'm wondering if i should get a second pump?
or oxygenating tablets?

Going to clean it all out today, and do a half water change.


The water colour is ok, and the are fed frozen bloodworms each morning, a little flake fod in the evening.
I do not feed them on Mondays as advised by my pet store, to help keep the tank clean.

Please help!

Answer
Hello,

It sounds to me like you have a water quality problem. You should try and get your water tested/test it yourself for nitrite, ammonia and if possible, dissolve oxygen. Any of these could be the problem. If nitrite or ammonia are high, it can cause decreased amounts of dissolved oxygen, as well as gill damage, which could be why your fish are gasping. Also, is dissolved oxygen is low then your fish are probably trying to get their air from another source.

If you do have a nitrite/ammonia problem, cleaning it and changing the water is a good idea. You should also add a denitrifier to your tank. Cycle is a good one. Closely monitotr your conditions until they get better.

If low amounts of dissolved oxygen are the culprit, then consider adding another airstone, or direction the flow of your filter output to the surface of the water if it isn't already, to agitate its surface and allow more  oxygen to be dissolved into the water.

I hope this helps.

Good-luck,
From Stephanie