Scavenger Fish Death Mystery

SumpNFishy

I seem to have issues keeping scavenger fish alive. Cory cats, flying foxes, even plecos never seem to live very long in both my established tanks (29 & 95 gal).

Occasionally I?ll get a hardy pleco (common) to live a year or more, but usually every scavenger type fish I buy dies within a few weeks, sometimes days. These tanks otherwise support a large variety of tetras, mollies, zebras, etc, most of your common community type fish.

I start with RO water and have added extra filtration over the years with no luck. My ammonia & nitrites are very low but sometimes if I go too long with water changes my nitrates get up to 40 ppm. Both tanks have live plants which do well with my lighting. The gravel is a common type purchased at my local pet store.

I have totally drained, cleaned and recycled one of the tanks, but I still find that tank is a death sentence to any bottom feeder I place in it.

Both tanks have under gravel filters but even if I don?t use them, the result is the same.

I always thought scavenger type fish were the hardiest type (especially plecos) but it doesn?t seem to be my luck.

My large tank has driftwood in it as well. But this last weekend the pleco I bought and placed in there died within 24 hours (the cory cat the next day). And both plecos died that I put in smaller tank. I tested my water and one had a high PH of 8.0 but other than that everything was fine in both tanks. The pet store also tested my water and came up with nothing obvious.

So my question after all this drivel: What will kill scavengers that doesn?t effect other fish?

Ironically I have a 20 gal tank with my wife's 2 large goldfish and a very happy pleco in what we know is very nasty water.

jwurm

I thought plecos were tropical and needed heated tanks. Can they survive in the cold water that goldfish do better in?

SumpNFishy

Actually I do have a heater in that tank. As long as you feed Goldfish, they will survive in just about anything. They are probably my oldest fish...

orb4me

Maybe you have a "killer" fish. I got rid of a rainbow shark, then a blue lobster, and still was missing fish. not dead, just plain gone, It was the rope fish. Do your fish look like they have been attacked? What does the fish store say when you take them back? Maybe you are putting the new fish in the tank to quickly and not giving them time to aclimate properly.

SumpNFishy

This has been ongoing for a few years so the turnover of the general tank populations would eliminate that. And I introduce these fish the same as the other, floating the bag in the water for 30 minutes or so before gently poring them in.

Last night got home and found the "Replacment" pleco had died in my 29 gal tank. He had looked very lively when I left in the morning.

Does anyone know what scavenger fish would be more sensitive too? The pet store mentioned the plecos like hard water. But in my larger tank where the pleco and the cory cat died, the water has a PH of about 7.0.

One person mentioned the water chemistry might be different around the bottom of the tank but in the 95 Gal tank I have installed 2 Powerheads with reverse flow on the undergravel to create good circulation, 2 Marineland Marineland Emperor 400 BIO-Wheel Powerfilters, and a Marineland C-220 Multistage Canister Filters so the water quality is pretty good.

I'm just plain stumped on why I have this issue with one type of fish.

oOOOo

Did you ever solve this mystery? Was it the nitrate levels?

SumpNFishy

Short answer: No

Long winded answer: Not really sure.

Since this I first posted this on the forum I have spent a lot of time reading and browsing through this and other forums. Played around a bit more with how I do water changes. Ended up completely redoing the 29 gal tank with new substrate, added driftwood, more plants, and better filtration (added a canister) and removed the undergravel filter system. Other than one weird ammonia spike it?s been pretty stable (Lost a few neon?s in that one). And I have a perfectly happy Pleco living in there now.

In the larger tank I?ve done nothing more than water / filter maintenance and all the fish along with the Pleco that has been there for about a year seem to be doing well.

With good filtration I really only need the Pleco?s to help with algae control and don?t really need any catfish at all. So at this point each of my 3 tanks has a Pleco and for now I plan to leave it at that.

I?ve also learned a lot more about water parameters and have added more test kits to my master kit as I didn?t really pay attention to water hardness before. I had been only using RO water and now I occasionally add a gallon or 2 of my well water to add minerals for buffering during water changes. I also added driftwood to the 2 tanks that didn?t have it.

Based on the way I take care of my tanks compared to others on this forum, all my fish should probably be dead. With full time job, part time business, other hobbies, other pets, etc, etc, this really is a part time hobby for me. I do water changes about once a month if I?m lucky. Most of the time my water parameters are good except high nitrates (140-180 ppm). I?m not really able to determine if this is bad as I?ve read several different thoughts on this. On that point the only thing I think everyone totally agrees on is ammonia / nitrites = BAD. And high nitrates usually means no or little ammonia / nitrites.

So for now I?m trying to improve my tanks by making them less maintenance intensive by adding things to stabilize the water (live plants, driftwood, minerals, etc), lightly stocking the tanks, and adding plenty of filtration. If I have learned anything since I got back into this hobby 10 years ago (did it as a child too), it?s that you cannot have too much biological filtration!

I really enjoy seeing the little cats scurrying around the bottom of the tank in their constant quest for food. But something about how I take care of my tanks seems to be deadly for them only. So for now I?ll spare any more deaths and settle for the Plecos that are doing fine now.

Now if I can just figure out how to setup an automatic water change system??..

orb4me

Sump: Glad to hear things are getting better for you.

There is a lot of web sites about automatic water changing systems for a fish tank, maybe it would be worth looking into for your situation.

oOOOo

Interesting. I seem to have the opposite issue. My water source has nearly unacceptable hardness: 120ppm. Seems I should be looking into RO to relieve the hardness rather than local water to relieve the non-hardness. (Not sure non-hardness is the same as 'soft'. Hmmm. More research...)

Thanks for finishing the story!