Tank disaster please help!!!1

[Meld]

Need some serious help with my 50 gallon tank. It's temps are 79 which stays that way all the time. All the readings are in normal range. No nitrite or ammonia, and nitrates are below 20. In the last couple of weeks I've lost a total of 10 or so fish in there including all my kuhlie loaches. Up until now I hadn't seen any signs of disease at all until my fiance noticed on one of my rummy nose tetras that half her body had turned completely white. It looks like a fungus but I've never experienced this before. I'm only left with 6 cory cats, 1 angel, 2 snails and 2 rummy nose, 4 checkered barbs, and 2 gold barbs which I think may have been the carriers of whatever it was. Oh and I have a rainbow shark who is 4 years old. I want to get it under control, but not sure if I'm doing things right. I used maricide in the tank as the directions suggested and hopefully that will help, but any other suggestions would be greatly appreciated. Oh and I'm almost 100% positive it's not ick, since I've delt with that before and this doesn't look anything like it. Thanks for any help you can give me.

[OrionGirl]

Any white on the dead fish? Something that sweeps through with such high levels of fatalities is pretty scary stuff, and if it's viral, there isn't any effect treatment. If it's bacterial, maracide is a pretty good choice--it's a broad spectrum gram negative and gram positive treatment, if I recall correctly.

Were the barbs recent introductions?

[Mantis_22]

The loaches went for a reason at first with all common sense, no immunity let alone no scales. Was there any white fungus or cotton like sheds on the corpses? Also if you ask me the cories will be last to die for sure if the tank isint treated. Im guessing this is a Strong Fungus outbreak in your tank. I may be wrong...

[Meld]

Yes the golden barbs were a new introduction to the tank. *sigh* I think that's where it came from. The ph in the tank is the same as it's always been 7.5 and I can't think of anything else it could be except a disease. I hope that the maricide will help my fish that are left over. Should I do any water changes while doing the treatment? or should I leave it until the treatments are over?

[scott]

One, if you have already lost ten fish and still have those left that sounds like an awfully crowded tank. Could it be an ammonia spike or possibly a case of bioacidification? I would think either one of those would knock off some fish pretty quick, especially the sensitive ones.
Second, could it be "neon tetra disease"? Isn't that a parasite?

[Meld]

I don't think it was crowded. Most of the fish that died were all very small except for the kuhlies that died. There are 17 fish left in the tank but most are under 1 inch except for the angel and the shark and raphael cat. I do once a week cleanings on the tank and there are 2 aquaclear 300's running and I've never had a reading of ammonia or nitrites at all since the tank was cycled 2 years ago. The nitrates are under 20. I've always been strict with cleanings and the most I let it go is a week and a half before I do another cleaning. I'll post the information I gave on another forum to see if it gives you any help.

Behavioral Changes-How is the fish acting differently?

**Any abnormal behavior-Active fish which has become inactive or inactive fish that has become active
-Before the kuhlies died they were not eating like normal but no visual signs of any disease.

**Trouble swimming in a straight motion, Head pointed down or up, whirling, lays on the bottom of the tank
-The fish that had the white film on her was swimming very aquardly.

**Loss of appetite
-The kuhlies were not eating like normal, but the other fish seem to be eating very readily at the moment.

**Hiding
-no

**Darting around the tank
-no

**Lethargic (Sluggish)
-no

**Is the fish rubbing on objects in the tank
-My shark did look like he was scratching the other day, but I've seen him do that before.

Basic Information about the Tank:

**Size in US gallons, UK gallons or litres
-50 gallons

**Length of time the tank has been set-up
-2 years

**Do you follow a regular maintenance schedule
-once a week

**Type of Filtration
-2 aquaclear 300's on the tank

**Whether or not the tank is aerated (airpump & airstone)
-no

**Temperature Farenheit or Celcius
-79 Farenheit

**Water Conditioners you use on a regular basis (dechlorinator, plant fertilizer, salt or any other chemicals)
-Aquaplus

**Live plants or plastic
-plastic

**Any medications you have used recently (Brand Name and dosage amount)
-I used maricide for 1 day so far at a dose of 1 drop per gallon (50 drops)

Information about the Water parameters: Please give the actual results if you can

**Ammonia
-0

**Nitrite
-0

**Nitrate
-20

**pH
-7.5

**gH
-not sure

**kH
-not sure

**Is there any aquarium salt present, how much
no

Information about the *other* Fish:

**What Species in the tank
-6 cories
-1 angelfish
-1 rainbow shark
-4 checkered barbs
-2 gold barbs
-1 raphael cat
-2 snails
-2 rummynose tetras

**Are you witnessing any aggressive behavior between fish
-no

**Total number of Fish
-17 and 2 snails

**Any Invertabrates present
-2 snails

The list of fish that have died so far are:
-1 rummynose
-3 gold barbs
-5 kuhlie loaches
-1 checkered barb

I hope some of this helps....I will be testing the tank again today at some point and I will give you the readings I find in it. The readings I gave you were the ones I got 2 days ago, but I will do another reading today and let you know what it says. Thanks for all the help you have given me so far.

[btowntaz]

I had something similiar a few years ago. I was never able to stop it. Wiped out most of the fish in my tank. Even my prized 5 year old fancy goldfish. I was told it was Ich, but was never able to confirm it. I added medicine to the tank, but with no results. All I can say is get a quarentine tank. And good luck.