Fish w/ labored breathing and swim uncontrollably

[joels3400]

So over the past month I've lost 4 fish with very similar deaths. They all seem to sit on the bottom of the tank for about a day and then will swim uncontrollably (spinning, upside down, sinking). A few hours later they die.

I do 2-3 water changes a week since this started happening. Eventually treated with Eyrthromycin which seemed to help but then another one died. Then, I tried General Cure and that helped me for about 2 weeks with no deaths.

Even though the symptoms indicate possible swim bladder, I really don't think that's it. I only feed my fish every other day and have been switching how I feed them so they don't eat at the surface.

The only other thing I can think of is that my aquarium stand is an old Cedar dresser and that's where I've been keeping all of my fish stuff (net, vacuum, food). Could this be toxic to them?

Any information would really help as I am extremely stumped by this.

 

[Delapool]

Hi, any pattern - like deaths after a pwc or anything? Have you treated with meds or changed anything in the tank?

Also do you have water readings for ph, ammonia, etc.

It does seem odd and possibly something in the water. Is there any oil coming off the wood and onto nets, etc?

 

[joels3400]

It's been random when fish have died. Sometimes after wc and sometimes not. I treated with erthromycin and general cure.

I don't see any oils on the net and the dresser is over 50 years old.

 

[joels3400]

Ammonia has been 0 and ph is about 7.8.

 

[Delapool]

It all sounds good. I used to have a fish tank on an old table which got oiled every week and never had any problems.

Were they all the same fish type?