Fish Dying Everyday!?!?!?

[Bettatamer]

Two weeks ago in my 29 gallon freshwater tropical tank I noticed one of my fish had gone missing. I took all the ornaments out and found her dead, It looked like it was there for a while. The next day the water was really cloudy, so I did a 75% water change. Since then I've lost 2 platies, 1 Cory catifsh, 1 rubber-lip pleco, and 1 guppy. I have a guppy and a molly that are looking pretty bad too. They won't eat anything. I keep doing large water changes, but nothing seems to be helping. Now this morning I noticed little dark brown spots that look like 'spores' on the sides of my tank. Whats going on? How can I fix this? The 'spores' are too small to get a picture of.

 

[Ch4rlie]

Hmm, think will need some more information before we can proceed any further really.
 
1 - how long have you had this tank?
2 - is the tank cycled?  http/www.fishforums.net/index.php?/topic/421488-cycling-your-new-fresh-water-tank-read-this-first/
3 - water parameter readings would be most useful. ph, ammonia, nitrite and nitrates if you have that one. 
If you do not have a liquid test kit, try your LFS to test you tank water for you, if you do this, make sure you ask for specific readings, not the usual "it's fine" reply.
4 - your water change routine? weekly, monthly, percentage of usual water change etc
5 - do you clean your filter and media? if so, how do you do this normally?
6 - have you added anything new at all to your tank? stocking, decor, plants, substrate etc
 
The more information you can supply the better for us to get a clearer picture of what may be happening in your tank. No such thing as too much information IMO.
 
Sorry for your losses by the way 

 

[mhancock]

I agree it's hard to answer without more info, but people on here will try to help. My first thought is was the new 75% water dechlorinated but that's just a guess...

 

[Bettatamer]

I can't get the water information, but have had the tank for about 2 months now, it is cycled, my water changes are weekly,I clean out the filter cartridge every tank cleaning by running it under some water and squeezing it until nothing comes out, and I added one new fish, the one that went missing.

 

[Ch4rlie]

Ah, cleaning the filter every week and running the sponge under tap water is the cause there am afraid.

You should never clean the filter sponge media under the tap, this kills the bacteria.
Am pretty sure you have NO bacteria anymore.
That affectively means you tank is no longer cycled. You will need to do a Fishless cycle again am afraid.

Basically your fish have been dying due to ammonia poisoning since there will be no bacteria to deal with the ammonia that fish produces.

For your information, filter media should only be ever cleaned in old tank water and very, gently squeezed just to get rid of gunk but not the bacteria.

Also when it comes to cycling the tank again, you will need a test kit really.

Sorry to be the bearer of bad news for you.

 

[mhancock]

I can't get the water information, but have had the tank for about 2 months now, it is cycled, my water changes are weekly,I clean out the filter cartridge every tank cleaning by running it under some water and squeezing it until nothing comes out, and I added one new fish, the one that went missing.

If you're running it under the tap water then there's the problem - the water contains chlorine which is killing the bacteria!  You must clean the filter sponge etc in water you've taken out of the tank before you dispose of that water.

 

[Bettatamer]

I do, and I use water conditioner. I think it was just that batch of fish as I haven't lost any fish in 3 weeks :3 glad that's over. I set up a 5 gallon quarantine tank now, hopefully that will stop any future problems!