Freshwater Bristleworms Killing my Loaches? Picture Included

[soul-hugger]

Lately I've had some unexplained fish deaths in my 55 Gallon tank - too many just to be coincidence. It started out with just a few Kuhlis dying here and there, and I figured since they were mostly the same age that perhaps they had come to the end of the line. The bodies had an odd look, and seemed to be white, wrinkled, and shriveled, almost as if they had nothing left inside. I work in a pet store and have seen many dead fish, so normally they don't bother me, but these were quite frankly disgusting. They could not have been dead longer than part of a day, since I check the tanks daily.

But like I said, I didn't think much of it at first, chalking it up to old age or perhaps something bacterial that I hadn't figured out. No new fish had been added to the tank in over a year, and the fish dwelling in the upper strata seemed to be largely unaffected.

The other day I found a Schistura dead, and once again, thought that perhaps the fighting between the two Schistura I have in the tank had finally come to a head. It was strange, though, because I noticed some small, regular wounds in its underside.

Then today, as I was cleaning the gravel, I saw something that didn't belong. It really gave me the willies because I wasn't expecting it: I had sucked up some kind of funny looking worm.

I got to digging around in the tank and found a few more. They are up to three inches long, red in colour, and have bristles down both sides. On one end, the bristles seem to be more prominent, and look as though they may be barbed. They move in a snakelike manner, slithering in the water and then retreating to the gravel. Honestly they look like something out of a horror film. I have caught a few of these and preserved them in a jar of isopropyl alcohol, hoping to find out more about them.

I now think I may have found a culprit for all these fish deaths. Here is a picture of them:



Anyone know anything about this?

Thanks:)

[splendid100]

I have red worms in my tanks. I have never looked at them under magnification. To the naked eye my worms look smooth. Maybe my worms are not the same as yours? Identifying aquatic worms is something beyond my ability. Maybe a zoologist who has specialised in studying this subject will be able to identify them for you?

My experience with my red worms has been positive: I bought a miniature pond lily from a garden centre about 9 years ago. It came rooted in clay. I planted the clay into the first tank I was setting up. The lily out-grew the tank (not so minature as I'd been told!) I removed the lily and replaced it with other plants bought from an aquarist supplier (those plants came as cuttings and guaranteed free of animal life). Some time later I found various creepy-crawlies in my substrate e.g. something that looks like an aquatic woodlouse as well as the red worms. The red worms seem to eat detritus and keep the substrate fresh and the plants grow well as a result.

Over the years, every time I set up a new tank, I add a couple of scoops of 'matured substrate' from the first tank and leave it to 'settle in' for a few weeks before adding any fish. This ensures there is a population of creepy-crawlies in the tank when the fish go in. Different fish seem to love eating these creepy-crawlies (e.g. my catfishes, loaches, gouramis).

All of my tanks have this mini ecosystem and it seems to be healthy. The most staggering effect was when I set up a tank for goldfish. I added four 3" goldfish to a 'seeded' month-old new tank and found that overnight the goldfish had begun breeding. The tank was full of eggs the next morning. Small goldfish in a 3' x 15" x 15" tank are not supposed to breed -- tell that to the goldfish!

As for my current tanks, they are full of plants and shoaling fishes, catfish, gouramis, cichlids, and loaches. Most of these fish breed regularly (only the otocinclus and synodontis catfish and clown loaches have never bred). I don't have space to raise fry so I leave them to take their chances in the community. Each year a few fry survive -- in part because the tanks are full of bogwood, ceramic 'caves', and heavily planted so the fry can hide and in part because there is all this natural food around even for tiny fry to munch on, plus I understock when I set up my tanks so the community can grow naturally to its optimum level. I call this a success.

I find that my big clown loaches eat all the red worms in their tank so I keep hoovering the substrate of my other tanks, collecting the worms from the waste water, and putting them into the loaches tank to re-seed it. I do this at least once a week. The loaches have grown well on this diet. The loaches, catfish, and other worm-eaters seem to love burrowing into the substrate hunting for the worms and I think it is good for their minds to have this sort of natural activity to keep them stimulated.

Because they have this natural food in their tanks, I feel happy about going away and leaving my fish for a weekend or so. I know they wont starve. I have kept fish for about 9 years and I don't have any health problems in my tanks. Some of my fish have died of old age but most of my original fish are still going strong and many of my fish are second or third generation home-bred fish.

I do feel rather guilty about the fact that the worms and other creepy-crawlies get eaten by the fish but I console myself with the thought that they seem able to burrow deep into the substrate and often escape to live and fight another day.

My hope is that the worms you have are the same as mine, and thus a bonus for your tank. The reason for your fish deaths would then have to be found elsewhere -- maybe old age as you say or maybe an infection. But if you are dealing with a different species of worm then maybe they could be parasites or carrying an infection that is harming your fish. I wish you every success with finding a solution.

Final comment -- I would recommend buying plants from a garden centre instead of an aquarist supplier / petshop. The plants will be rooted in clay and will bring a load of useful invertebrates to your tank. Given there are no fish in garden centres, the invertebrates are unlikely to carry parasites or harmful diseases so your fish should be fine (this is true for the UK -- might not be true where you live so please check first before following this advice). I think some people try to keep their tanks totally sterile and their fish suffer as a result. Fish evolved to live with creepy-crawlies and in a 'mixed' ecosystem. If we give them as much of a mix as we can manage then I think our fish will be happier for it.

[andyroo]

They're polychaete worms. Annelids, yes, but not earthworms. If only 3" I'm surprised your fish don't eat them.
I'm not familiar with the FW version, but in the marine system they can be serious predators... though also can be scavengers.
I think your fish are dying from something else (Water quality? Contamination? Chlorine) and the polychaetes may be eating the corpse, though I could be very wrong. The worms may also be indicators of another issue- possibly water quality.
Take the bottle/sample down to U-Sask and see if you can get them ID'd. That will at least tell you what they are and eat, and wether they are the issue. Also test your water.
A