Need help. Fish dropping dead.

pH - 7.6
Ammonia Level-0
Nitrite Level-0
Nitrate Level-5
Water Temperature-78
Tank Size-55 gal
How Often You Do Water Changes And What Percent You Change-1x wk-15%-20%. Approx 9-10 gal.
How Long Has The Tank Been Running-2+ years
Testing supplies: API master test kit.
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I am having a huge problem with my tank. It has been running smooth for the longest time. About 2 months ago and started having a problem w/my plattys. They started to have clamped fins and slowly started dying off one by one. I have a community tank with neons, plattys, mollies, guppies and endlers. Until two days ago only the plattys were dying off. Now i have lost 6 endler females in the past two days. Im guessing there is 25-30 fish in the tank. Due to the number of fish I make sure the parameters are always as ideal as possible. With the exception of the nitrate the others always remain safe. The nitrate will move up and down but usually remains @ 0-5. The highest reading I have ever had is 40, which only lasted for one week. That reading was over 6 months ago and no fish were lost during that time frame. I have done nothing different with my tank to cause this problem. I tried to medicate the tank w/Rid Ich over the wkend. I tx'd the tank on Sat and Sun. to see if that would help w/the clamped fins. I thought one of the two surving plattys looked a bit better, but I started losing the female guppies, so I stopped the tx. I did a water change tonight to see if that will help stop the death trap my tank has become. Any thoughts of help would be greatly appreciated.

 

Are you using any chemicals in the tank? Such as a dechlorinator or anything else?
*I use API Stress Zyme & Stress Coat with each water change

If this were my tank here's what I'd do:
1. Check your test kits expiration date...regardless, I'd still have my water retested at my lfs.
*I could not find an exp date on my text kit or chems. The water has been tested at my LFS and Petsmart multiple times. They always say the water quality is great based on their test.
2. I'd temporarily shut down the filtration and check my media and filters to make sure they didn't need serviced/rinsed/changed.
*Filters have been changed 4x over the past 2 months. I usually went about a month before changing the filters in the past. I have rinsed my media bag but not the sponge.
3. Then, while the filters are off I'd do a good siphoning/stirring of the substrate to make sure any muck in there is removed (and to check to make sure there are no more dead fish that might have been missed)...roughly removing about 50% of your tanks water.
*The substrate is clean and I stirred it over the weekend. I took about 15 gals out over the weekend and another 10 gals tonight. No dead fish in the tank.

4. I'd dose for the entire tanks volume with PRIME, refill & turn the filters back on.
5. And finally I'd add Seachem De*Nitrate which I'll link below.
http://www.seachem.com/Products/product ... trate.html

6. And I'd probably add an airstone to increase oxygen just to be on the safe side.
*I already had added air/oxygen with a 6” air bubbler.

Are these recently purchased fish or ones that you have had for some time?
any other signs besides the clamped fins? (bloated belly, gasping at the top for breath, fuzzy/grainy/gold flecks or spots, cloudy eyes)?
*The fish that are dying are older established fish. I purchased 4 fish about two weeks ago and only one has died.

Anyone in the tank that could be turning nasty and wreaking havoc on your fish and stressing everyone out? (ie. pleco..incompatible tankmate)
*No bullys in the tank. All community fish: neons, platies, mollies, guppies & endlers. Thanks for any insight you can think of. I understand the questions about water quality, but I really do not think that is the issue. I am confident the water quality is above avg since all test come back where they should every time. I forgot to mention the tank is planted and all plants are in good health. I have hornwart floating on the top which I have to thin out every week. I add a liquid fertilizer for the plants. I have been adding the fertilizer for years without any problems. The exp date on the fert is not expired.

 

man, you got me on that one...maybe just simply old age if they were purchased around the same time?
* The platies had been in the tank for about a year. They included the ones I purchased plus the babies. I was probably on my 4th gen on the platies. I had all ages and sizes,but now none.
. The endlers were all raised from fry except the first two, I may have one or two left.
/
I wasn't really thinking water quality (moreso thinking pockets in the substrate)...and if the lfs has tested the water and it came back good then that blows the idea of a bad test kit out of the water.
/
Not familar with the stress zyme product (although I have seen it in stores)...but as long as it removes the baddies and actually works then obviously no issues there. I still suggest prime though (last 24 hours and would only require a bit over 1/2 cap for a 55g...and plant/invert safe).
* Ive used prime in the past. I think they were out when I needed it last time and have been using this stuff. I ve used both in the past w/o any problems.
/
I dosed in the past for plants with seachem and never lost anything (even when a few times I accidentally spilled more in that I had wanted)...and being you've used the same product in the same manner for years I wouldn't suspect that as a culprit either.

*Thats the same stuff I use now and have never had a problem with it either.
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Makes me go back to old age...poor quality stock (healthwise like from lfs).
* I can understand some loss due to age, but I know some of the female endlers were not much older than 2-3 months. I didnt add any new fish before the die off. I added the four I mentioned and three of those are still alive. I loss another female guppy last night. No sign of distress or any other problems.
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Increased water changes, De*Nitrate, & Uv Sterilizer are all options that couldn't hurt though.
/
I just checked my water and everything is the same except the nitrate is @ 0 instead of 5. Pulling my hair out with this problem. I wish I could figure this one out..........hopefully the death parade will stop soon. lol

 

Readings today:
pH - 8.0
Ammonia Level-0
Nitrite Level-0
Nitrate Level-0
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Ive lost three more fish since my last post. Two today. I had to put one down, a female guppy, and this was the first one that had any signs of a problem. There was a sore on one side that looked like a circle in the flesh with some red around it. No signs of velvet per the prior post. I'm going to try and figure out how to post a photo to see if that helps.

 

I have no idea why the PH is going up. I added some PH decreaser yesterday and today. The PH was 8.2 yesterday. I'm going to do a 20% water change later tonight. Still trying to figure out how to add the picture of more poor little guppy.

 

Pics of fish.. Thanks for the help getting the pics uploaded.

 

If its a bacterial infection would the other fish that have died off not show any signs?

 

Readings today:
pH - 8.0-7.6; depends on which family member looked at the tube. LOL
Ammonia Level-0
Nitrite Level-0
Nitrate Level-0
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Well the death spree continues. 5 more fish are hangin' with Elvis. I did another water change over the weekend. I can not figure out why the pH is elevated. I checked the water straight from the tap and it was 7.4. After the water changed my tank was 7.4 on Saturday. Im treating the tank w/MelaFix and feeding them a medicated food for baterial infections. All the dead fish had no external signs of injury or illness. I keep hoping to just go a few days w/o losing a fish. I did a really good cleaning this weekend. I have a plastic tree trunk decoration and I took it out and gave it a really good cleaning. So now Im sure there is not much waste in the tank. The plants are all doing fine. Since all my platies have died off, its the guppies turn to pay the piper. Up until I lost my last platty I had probably only lost a couple guppies. Since the last platty died, Ive probably lost at least 10 guppies.