Jump to content

Strange invader in my shrimp/cory tank.

Recommended Posts

Last night as I was shutting things down for the night. I noticed some kind of worm or lava in open ended "cocoons" that kept wiggling (I think to keep water flowing through the "cocoons"). Every once in a while, they would stick their heads and about half their body out and look like they were feeding on the Java moss pressed against the wall of the tank. I also saw what looked like tiny mosquito larva swimming to the surface. These were much smaller than mosquitoes or the blood worms.

I have been having a very hard time with what tank. I think it is a bacteria bloom from over feeding. The ammonia and nitrites are both zero. But you can hardly see through the water in the tank. A week ago, I saw tiny cory fry wiggling through the water, but haven't seen any in 2 days. I don't know if they aren't there, or if the water is too cloudy.

Tonight when I lifted the top to feed the corys, the tank smelled trashy, not sulfur, like at low tide. I took the lid off and the corner of the tank nearest a brink light outside the tank was covered in tiny dead flies. I wiped them out and wiped everywhere about the water line. I should taken photos first, but didn't.

I think it is some kind of mig or fly that has it's larva in moist soil. I looked up white flies, but their life cycle doesn't need wet soil or standing water.  I had been trying to grow the Java moss in a very shallow pan with the water level almost covering it for a few months, with plans of using it to build a moss back wall for my 55 tank.  When the corys started spawning in the shrimp tank, I added the Java moss to provide lots of cover. 

I left the top off the tank, but will put it back before I go to bed. I'm not sure what is going on in the tank or what I should do about it. I went through info on every aquarium pest I could find, but nothing looked or sounded like this. The cloudiness might be from over feeding, or from these things. I now have 2 sponge filters and and air stone in the 10 gallon half cylinder tank. I moved the air stone to the corner where I saw these things, and the water got cloudier. It might have been food that settled in the moss, or it might be from these things. It is getting late, but I will do a 25% water change before bed.

Any idea what might be going on and if these critters are helping or hurting my fish?

 Anyone every see anyth9ng like this before?

Link to comment
Share on other sites

@nabokovfan87 The adult "flies" that emerged after I cleaned the glass are above. Below are some attempts to photo the larva on the glass. I think they are also on the hardscape too. It took for ever to get the one cocoon marked. Sorry, but I don't know this software at all.

Java moss with cocoons:


more larva1834999414_larva1s.jpg.f40c7658500219461f2c9f0f6398c529.jpg

more larva1416291917_larva2s.jpg.990a1ca4c054c67e73223af34288a9e5.jpg

hardscape seems to have black/brown cocoons too:







hardscape 1 s.jpg

Link to comment
Share on other sites

The moss came from bits from several tanks over the last year. Every time I bought plants online, I bought more java moss. It has sat in an open shallow pan in my living room for months. I would bet the flies or what ever they are are local. I have no idea if they are part of the problem or a red herring, so to speak.

I'm guessing the best thing to do is to stop feeding that tank until the cloudiness clears up.

I started writing this at 9:00pm, I got it posted, and then started fighting with my cell phone and Gimp to get the photos scaled and posted. Then I started the water change and tried to get better photos of the adults. It is after midnight now. It will be well after 1:00am before the water change is finished.  I don't think I was born to be a fish keeper.  



  • Sad 1
Link to comment
Share on other sites

I really can’t tell by the photos but what you describe sounds like caddisfly and their larvae. Midge larvae tends to be free swimming and bloodworms which you see in the frozen cubes at your LFS is what most species larvae looks like. Although there are a few that more closely resemble mosquitoes larvae.


Caddis flies are a bit more picky with where they lay their eggs typically a stream or pond with significant sediment, but they have definitely made “mistakes.”


If you can get better photos of either I could probably point you in s better direction 

Link to comment
Share on other sites

@Biotope BiologistThe "cocoons" the larva were living it were attached to the glass and you could see the larva moving it the cocoon. it kept a steady flow of water moving past it, inside the stationary cocoon. it would half leave the cocoon to reach a branch of Java moss, and the retreat into the cocoon, but the cocoon never moved. Here in central NY you always see spider webs full of these flies near lights., they are much smaller than mosquitoes. I will see if I can get some photos of those adults that have gotten caught in a web. I'm sure there are some in the corners of some windows are the cottage. The larva in the cocoons, had a shiny shimmery surface. They were much to small for my camera to focus on. The Caddis flies I saw on YouTube were dragging their cocoon that the built around over their abdomen.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...