Need advice on my Giant danio

[Sparkler]

Hello everyone,
I'm fairly new to this hobby & need some urgent advice on one of my giant danios.
I have 2 of them one is fine & the other one seems to always be gasping he/she is
always staying near the surface.When it swims out the other one chases it back into
a corner.
I've checked & re-checked all my fish which i've stated at bottom,and cant find any problems with them,they all seem fine except the 1 danio's behavioure is bothering me.
I've also re-checked my water tests they read,PH 7.6--Nitrate 5--Nitrite 0ppm(mg/l)--Ammonia 0ppm(mg/l)
If anyone has any advice or help they can give me i'd be very grateful.
Thanks in advance.

Tank is,Rekord 70,Juwel 70ltrs size 61cmx31cmx46cm high
Fish..4 cherry barbs,4 platties,2 mollies,1 suckermouth fish,2 giant danios.
Set up in December 2002.

 

[bigfish]

Apart from the gasping is their any other syptoms that this fish is showing?

 

[Sparkler]

Hi there,
No thats what makes me wonder what could be the problem.
There are no signs of any fin nipping/fin rot ect.
All my other fish dont seem to be in any problem/stress,i'm really
what to do.

 

[bigfish]

Could be a lack of oxygen (possibly) you could add an airstone and pump to see if that helps, Is your daino hanging around the filter inlet (where water comes out)?

 

[Sparkler]

The danio is just at the side of it,but none of the other fish seem to be gasping & all seem well.I think i'll
try the airstone & pump to see if it helps,thanks for the reply & help.I'll keep posted how things go.

 

[Pufferpack]

With Danios being a shoaling fish could it be because one is dominant and the other is stressed? If this is the case you might be able to add 4 more to make a good sized shoal and reduce the stress on the less dominant one