Dying Fish

Hello to all fish experts out there! I just found this site tonight, and I'm hoping it's going to be the answer to my poor fishies' prayers!

My problem, simply put, is this: my fish are dying and I can't figure out why.

Here's everything I can think of to give as far as background info: 30 gallon tank. Aqua-tech power filter. Bubble wand and air stone. Temperature 76F. No live plants. Reverse Osmosis water. I do a 20% water change with vacuuming every two weeks and add Aqua-Safe water conditioner then also (I've been adding the Aqua-Safe only for the past month or so, and the fish had been dying prior to the additon of that and are still dying after using it). I've had the tank since November 2004.

Here's what's left in my tank (for tonight, anyway...who knows what will be alive tomorrow): 1 neon tetra, 4 zebra danios, 1 platy, 1 swordtail, 1 black molly, 1 tetra (I can't for the life of me remember the name of it...kind of big, silver, black tipped fins). If this seems like an odd combination, all these guys used to have mates...until they died.

My last death occurred this morning....my last corydora. He was swimming around last night as perky as could be. When I got up this morning he was lying on his side on the bottom of the tank with his gills barely moving.

I've tested the water using those quick strip tests: Ammonia Quick Dip and the 5-In-One Quick Dip. The results were all in the optimum to normal range. And just to double check those results, I took a water sample in to a pet shop and had them test it...everything was in normal range.

My water, right now, has a cloudy look to it...not green tinged with algae, more like a white tinge. I've been feeding the fish less (but not so little as to starve them) in case too much food was causing that problem, but the cloudiness remains even in spite of the regular water changes.

Now to the dying part: they die. The fish show no signs of illness or distress prior to dying. In fact, to my untrained eyes, they look pretty perky and happy--until I find them dead. I can't even count all of the fish that I have found dead in the morning that seemed perfectly fine the night before. They only die one at a time (no mass suicides or anything like that), and their deaths don't seem to coincide with the water changes. This has been happening for quite a few months now, and I'm ready to pull my hair out. The people at the pet shop haven't a clue what my problem is.

I have one fish left from the initial set up of the tank...the big tetra. He used to have three fellow brothers/sisters who have since died.

Any advice would be greatly appreciated! I really want to solve this mystery and get on with having some healthy long lived fish. Thanks for reading! Hopefully when I check back tomorrow, somebody will have some new ideas for me to investigate. :help:

Black Skirt Tetra? I have no idea. Doesn't sound like what they said it was at the pet store. I'll have to check next time I'm there.

I've been using R.O. water from the very beginning (our whole house is on an R.O. system). If that's the problem, what can I do to fix that? I never even thought that was the problem since the person at the pet store said R.O. water was great for aquariums. Is there some type of additive I can put in the tank to make the water "healthier"? I think that sounds like a plausible explanation since, like I said, the fish show no signs of disease or distress before they die. Maybe their systems just shut down after being without certain minerals in the waer for a certain length of time.

We do have one faucet outside that comes directly from the well. Should I use that instead?

What about salt in the water? I've read conflicting reports on various web sites...some people swear by the addition of some salt in freshwater aquariums, others swear not to. Would that help anything?

The decorative things in my aquarium are: plastic plants, an artificial piece of driftwood (looks like it's made of acrylic and painted brown...a piece chipped off and it was white under the brown paint), a tall, tan "sand castle" (don't know how else to describe it...not sure of the composition....some kind of clay or glass?), and a small gray rock-type formation (again, made of some type of breakable material....). The driftwood and sand castle were bought at a pet store and the rock thing was bought at Walmart. I assumed they were fish friendly, but maybe not?

Thanks for your ideas. I really need to investigate this R.O. issue, I think. If anyone has any other ideas, please feel free to share them....my problem is probably something that many of you long time fish keepers think is a no-brainer. So, please, help my fish-sense grow! :read:

Okay, I'm heading out to get some R/O Right by Kent. I wonder if that would explain the problem with two of my guppies and one platy...they all ended up getting severely deformed humpback spines in the few months that I had them (before they died, of course).