HELP!!! FISH DYING FOR UNKNOWN REASON!

NOT SURE WHAT HAS HAPPENED. THIS IS AN ESTABLISHED TANK>SET UP FOR ALMOST A YEAR WITH NO PROBLEMS.2 WEEKS AGO I REMOVED 2 LARGE GOLDFISH THAT HAD BECOME VERY AGGRESSIVE. I ALSO NOTICED A LARGE AMOUNT OFSEDIMENT IN GRAVEL ,I REMOVED THE FISH<PUT THEM IN ANOTHER TANK<STIRRED UP THE GRAVEL<REMOVED CHARCOAL AND LET SYSTEM FILTER FOR 3 DAYS BEFORE RETURNING THE FISH>I RINSED THE BIO-FILTER AND ADDED 3 SWORDS AND 3 MOLLIES. NO PROBLEMS>THEN A FEW DAYS LATER MY BOYFRIEND BOUGHT SOME FEEDERS AND TADPOLES TO ADD TO THE TANK.THAT WAS A WEEK AGO>FEEDERS AND TADPOLES STARTED DYING THE NEXT DAY AND I HAVE BEEN LOSING FISH EVER SINCE. THEY DONT SHOW ANY SIGNS OF DISTRESS OR DIESEASE>THEY ARE FINE AND A FEW HOURS LATER THEY ARE DEAD>SOMETIMES SEVERAL ALL AT ONCE. I ALSO CHANGED 50% WATER WHEN I REMOVED THE FISH.

 

have u got a test kit? if u do check ur levels. maybe ur heater is broken check ur levels though that the main killer of fish

Peace Out Callum!

 

HI Babydoll. That sounds awful. Sorry your'e going through this.

Couple of possibilities:
- Do you often do substrate vacuuming? If you don't (like me :-\), it could be that air from your substrate with a high concentration of nitrates has just released itself, poisoning the fish, explaining the all-at-one. Please test the water for nitrates/nitrites/ammonia to be sure that's not the case.
- It could also be that the feeder fish were sick or poisoned in some way from something they themselves ate, thus killing the fish feeding on them? Do your 100% vegetarian fish (provided you have any. Algae eaters and the likes) also die en-masse at the moment?

 

NO. I HAVE NEVER VACUMED THIS TANK. AND NO AGAIN >THE 3 CATFISH AND 1 PLECOTOMUS ARE DOING FINE>SO FAR. AND NO I DONT HAVE A TEST KIT>HAVE NEVER NEEDED ONE. HAVE HAD 3 TANKS FOR OVER 10 YRS NEVER HAD A PROBLEM BEFORE JUST A COUPLE OF ICH OUT BREAKS AFTER ADDING NEW FISH.THATS WHY IM SO CONFUSED ABOUT THIS PROBLEM.AND ONLY 1 OF THE FISH FROM THE ESTABLISHED TANK HAS DIED>ITS MAINLY THE NEW ONES WE JUST PURCHASED,MAYBE IT WAS JUST A BAD PURCHASE.IT WAS A NEW STORE THAT WE HAVE NEVER USED BEFORE.

 

Oh sorry I've misread you then. I thought your older fish were dying too.

The veggies are OK? Mmmmh, perhaps my theory about the feeders beind dodgy?

To be honest, I hardly ever test my water nowadays. It's not what most of our members recommend though. I just make sure I keep up with regular maintenance (something like 1/4 to 1/2 water change every week, or more) and keep an eye out for anything alarming.

If I may suggest it, I would advise you to do a substrate clean. I am needing to do that too now, although I hate it as I have lots of decoration to displace and some hard to reach places. I used to love doing it, but now my tanks have too much stuff in which the fish love, but make it a pain to clean. It can poison the fish, though, if too much waste accumulates in the gravel.

 

I am thinking along the same lines as armadilo. Could be:

1) stirring up the gravel that had not been vac'd could have released some toxins that had been trapped in the substrate. It is possible that your older
fish have adjusted to that over time and are able to handle it, while the newer fish are having "system shock". One of the other members has a
horror story about killing off his entire tank by disturbing gravel that had never previously been vac'd or stirred up...I do not remember who it is at
the moment though.

2) you mentioned you rinsed off the bio-filter. Did you rinse it in tap water or tank water? If you rinsed it in tap water it could have killed off a good
portion of your bacteria. If you rinsed in tank water, this is not the culprit.

3) it is pretty common for feeders to be diseased. They could have brought something from the store to your tank.

 

sgould asked my 1st thought when reading the original post. what did you rinse the filter sponge in?

I think doing the API tests for ammonia and nitrites will help narrow down the potential causes as well as determine what to do next.

What do you use for treating your tap water? If you don't have Prime, i'd recommend getting some withe the API master freshwater testing kit.
How big is your tank?
What kind of air stones, wands, or curtains do you have in the tank?
What type & model is your filter?
How often do you replace the bags and how often do you replace the activated carbon?
Aside from the catfish (what type of catfish?) and the pleco (is this a common pleco?) what fish are left in the tank?
Do you feed them algae wafers and if so, how long do you leave the wafers in before removing them?

 

BIO-SPONGE WAS RINSED IN TAPWATER-BUT I HAVE ALWAYS DONE SO WITH ALL MY TANKS. AQUA TECH FILTER,NO STONES OR WANDS>DONT FEED ALGE WAFERS>CARBON FILTER IS CHANGED EVERY 2 WEEKS AND I ONLY REPLACE WATER AS IT EVAPORATES >USALLY WHEN I CHANGE THE FILTER>WARDLEYS CLHOR-OUT FOR TREATING THE TAPWATER>NOTICED ICH ON ONE OF THE FEEDERS SO AM NOW TREATING WITH WARDLEYS ICH-AWAY> HAVE ONLY LOST ONE FISH SINCE ORIGINAL POST BUT ONE OF THE FEEDERS HAS CLAMPED FINS SO PROBLLY GONNA LOSE HIM NEXT.
10 GAL TANK>20 GAL HANGING FILTER>2 TIGER CORY CATS>1 SPECKLED CAT>1 COMMON PLECO>1 MOLLIE>2 UNKNOWN WHITE FISH...WERE IN TANK WHEN RECIEVED>5 SMALL SWORD/MOLLIES LEFT FROM FEEDERS AND 10 SMALL TADPOLES.
PS. THANKS TO EVERY ONE FOR THE HELP!!!

 

It sounds like you might have old tank syndrome. Without knowing if your readings have been changing as your water gets more concentrated with toxins, it's hard to know for sure. Here's a great explanation of why water changes are necessary, and why the old fish are fine, but the new fish keep dying:



If this article describes your tank, you definitely need to get that master test kit ASAP, and you will be making gradual water changes and gravel vacs so you don't affect the ph too much at one time.