Figure 8 constantly swimming top of water. -please help
I am having a nightmare. I have been running my brackish tank for nearly 4 years. 6 figure 8's and a Colombian shark! Absolutely no problems at all with limited Maintenance.
As the shark continued to grow I have bought a new tank. Read, seeked advice and believe that I did not have to fully cycle the tank as I was transferring over my old filter and was going to leave that in for 6 or so weeks.
Anyway, setup new tank, waiting a week and then carefully bagged up the fish, transferred to new tank and slowly mix water etc before releasing them into tank.
After 10 hours later after all was looking good I noticed that 5 of the puffers where all floating at the top motionless. Honestly I thought they had passed away.
I panicked and so whipped them out straight back into the old tank. After 2 minutes 4 of them where visibly better, 1 remained upside down motionless (god knows but after 10 minutes he was back with us :) ).
The issue then comes that 24 hours later 2 of them are swimming along with their noses on the top of the tank. (In 4 years they have never done this!) even in my old tank.
Does anyone have any idea why they would be swimming on the top?
Even the shark seems to be breathing heavier with big gulps.
I am worried now I will loose all of them as I have no idea what is wrong.
I am put of now even considering moving them to the new tank in the future (if they survive! :(.
Any advice gladly received.