Fish gasping for no reason?
Hello all, I have a rather newbie-ish question. I have a 10 gal and my fish are sort of gasping, I guess. They've never done this before so I'm guessing that they're gasping?
Here's the situation. It's a 10 gal with 30w photoperiod 10 hours. Ammonia @ 0, NitrAte between 5 and 10 ppm (color looks right in the middle), pH around 7.4 (my kit shows 7.2 and 7.6 and it's between the 2) and out of the tap it's 7.6. I use liquid test kits and they are fairly new (6 mos old). I have a Rena XP1 canister filter on the tank (it's been running for 2-3 mos) and the tank has been set up for about 8 mos. I have 1 dwarf puffer, 4 otos, and 2 amanos. The temp is a little higher than usual at about 82 degrees. I unplugged the heater just now (I keep my apartment around 76 degrees).
Yesterday afternoon, I switched my substrate from inert sand to ecocomplete and tested the water after about 3 hours and all the levels were as above. i kept everything but the sand (didn't clean the filter, kept all the hardscape and plants). I put the fish back in around 7 pm last night and they were fine. I fed the puffer some live brine and she ate fine.
I just added an airstone in case they were gasping due to lack of oxygen (I have no CO2 running).
Is my assumption correct (lack of oxygen?)? What else can I do?
Thanks for any help,