Major Fish Death!!! 12 out of 16 dead!

leehound

I have had my tank for about 5 weeks. All the fish had seemed to be doing fine and looked very active and of course always hungry. But last night I lost 12 out of 16 of my fish. Right now I am just dumbfounded and don't have a clue as to what happened.

Details of the massive death:

Yesterday I noticed a lot of brown substance (alge?) forming on the glass and decorations in the tank. So I decided to clean the brown off and also do a 30% water change. I used a new spong and cleaned all the glass on the inside. I also took out some of the decorations and cleaned them with tap water. I then drained about 10 gallons of water from my 29 gallon tank and refilled with tap water and then added the water conditioner. Four hours later 12 fish were dead! I immediately checked the water with a test strip. The water tested within safe parameters.

My tank is a 29 gallon with 2 wisper filters running and a heater.

7 Tiger Barbs: Dead
2 Bala Sharks: Dead
2 Catfish: Dead
1 Alge Eater: Dead

4 Blue Gouramis: Alive but listless and little appetite

I did discover a mistake I made. Instead of 1 teaspoon of conditioner for every 10 gallons, I used a Tablespoon. Would that have killed the fish? Could it be something with the spong I used. It was new with no soap in it. Or could it be something to do with the brown stuff I cleaned off the tank?

Any theories?


thanks

Scott

jones57742

I doubt that the tablespoon vs the teaspoon had much to do with it.

A 30% water change with tap water probably did as you added the dechlorinate after adding the tap water. Only a very brief exposure to low concentrations of chlorine/chloramines is lethal.

You did not mention temperature. If your tap water temperature varied significantly from your tank water temperature an instantaneous change in the temperature of the tank water due to the induction of the tap water may have also affected the sudden deaths.

TR

leehound

Actually I added the water conditioner before adding the water. The temperature is something I did not think to check. Hmmm

lioness501

oh my thats awful. do u have exact readings for ammonia, nitrite and nitrate? also i would ditch the test strips and get a liquid kit like api master test kit. the strips r innacurate

willow

hi
would the disturbance of the substrate have
anything to do with it,by any chance ?
what is the substrate by the way.? (if you don't mind me asking)
sorry for your losses. :(

mHeinitz57

If the death was that soon it was most likely due to shock. Over conditioning the water isn't a problem, I don't even measure mine out anymore. It could very have well been temperature shock as Jones mentioned. Always try to get water that is close to the temp of your tank water. If you can't get it exactly, a little warmer is better than colder. A warm shock is less "shocking" than a cold shock. Also, if there was a big shift in pH from the water that was in your tank and the water you put in then that can have bad effects as well. Make sure you are careful with the sponges you use. Even if you don't put soap on them some are pre-treated with cleaning chemicals and soaps.

leehound

I know what killed them!

I now know what killed my fish. When I cleaned my tank, I had asked my wife for a new sponge. A sponge is a sponge, Right? As long it doesn't have soap in it, it should be safe. WRONG! I asked my wife for the package the sponge was in. On the back in small letters it reads "not for aquariums". The sponge is called "O-CEL-O" made by 3M.

From their website: O-Cel-O™ sponges are developed with 3M's unique StayFresh antimicrobial technology to resist bacterial odors.

Must be some chemical they put in the sponge that is a fish killer. And doing a web search reveals others having simular experience.

I am really glad I know what happened. Because as a new hobbyist, I was ready to throw in the towel. But now that I know for sure what killed them, I will rebuild my fish community.

Thanks to all for the response to my situation. I will take some advise, and get a better testing kit.

Scott

GW

Very Sorry to hear about your losses of some fine fish!

Your posting of this problem though may have saved hundreds...Thank You

mHeinitz57

thats why I mentioned this, i've had customers have the same problem before. This is why I just pay a little extra and buy algea scrubber pads from the LFS. I'm very sorry for your loss but i'm glad you solved the problem and aren't just giving up on the fish hobby. Good detective work too by the way

Julie's Julies

I am so glad you are not going to give up this fascinating hobby! I am new at it too and lost 8 fish...only to discover that my PH was way too high and the fish were getting stressed. It's definitely worth the effort to find out what went wrong and how to correct the problem.

Best wishes to restocking your tank!