Fish keep dying...

Hi Christian,

A couple of thoughts and a few questions for you.

Where your tank is barely a month old I would re-check your parameters. Make sure you're using good quality test kits that are not out of date. Generally speaking the ones that use test tubes and liquid are more reliable then the paper strip kind.

The tank is relatively lightly stocked but even still I think you'd be wise to bump up your water changes to 30% a week.

Questions:
How long does it take from the time the fish go from eating and swimming normally to sitting on the bottom? Overnight? A few days? Do they still show interest in food once they've started sitting on the bottom?

What are you using for a declorinator? Do you routinely add any products to the tank?

When you feed how long do you feed them for?

Any marks on thier bodies? Fuzzy growth? Nipped fins?

When they are sitting on the bottom do they try to swim but seem to 'sink' like they are too heavy?

Did all five fish that died go down at once? Had you recently done a water change?

Robin

It all happened very suddenly.

Click to expand...

How suddenly is important to know. With bloat you normally see a progression of symptoms over a weeks time. First fish start spitting out food, then they stop eating, you may or may not see long stringy white or clear feces. Fish may gasp and will become lethargic. Towards the end they may get a bloated belly. Also its more typical for bloat to effect one fish at a time.

It may be bloat, but I'm far from being convinced that it is-yet.

You mentioned you did a water change just prior to all this happening. Go over everything about the water change. Any chance gasoline or soap or some other toxic residue was on your fingers and got into the tank? Could anything toxic have come into contact with your water changing buckets or python?
Usually with a toxin in the water you'll see all fish react in some way so I'm not convinced that this is what is happening either. Do you pick up their food in your fingers when you feed them? This is one way a toxin from your fingers could be transferred to the fish and some would get more of it then others.

Check with your water company to make sure they haven't made any changes to your water supply and then I would do as Kim suggested and do a large partial water change and gravel siphoning. This is not to correct water parameters--but rather to remove some of what might be hurting your fish.

How about aggression in the tank? That's another killer that kills fast with few symptoms prior to death.

The only other thing that I know of that kills fish fast is a bacterial infection. Normally you'll see fuzzy growth or patchy areas on the fish but it can be an internal infection with few outward signs.

Please post back with additional info. I'd be interested to hear if there's any change in the sick fish's behavior after you do the water change.

Robin