# Ostracod/critter overpopulation



## dwalstad (Apr 14, 2006)

Below is a recent interchange with a hobbyist about an overflow of ostracods in his shrimp bowl:

_I'm currently dealing with a serious infestation of ostracoda and either daphnia or copepods. These small animals have overwhelmed my small (1 gallon, bubble filtration with a big piece of wood, moss ball, and heavily planted / lighted) red cherry shrimp tank. The tank gets lighting as you recommend, with a siesta in the middle of the day. The number of animals in my tank is easily nearing the thousands. They are starting to become so numerous that they are now dominating the water chemistry of an otherwise stable shrimp tank.

The "animalcules" are now congregating on the shrimp, maybe 2-10 at a time. I'm worried they will start killing the shrimp. One shrimp has died (but probably from improper molting; water is hard, so I'm not sure why).

I would really love to hear any advice you have on dealing with these ostracoda and either daphnia or copepods._

After recommending that he add a male guppy to clean up the critters, I got this response:

_Thank you for your advice; adding a guppy sounds like a great idea! I didn't realize they would do okay in such a small tank, this is good to hear. Unfortunately I won't be able to get one until the current health crisis abates, so the ostracods have free reign for now...
_

My new recommendation:

I searched the APC's (Aquatic Plant Central) shrimp forum for help on this. Yes, it does seem like other small fish (Endlers, White Cloud, Least Killifish) would very much enjoy solving your problem.

In the meantime, it would help to just clean the bowl and remove debris. Shrimp will eat flake food and big stuff (cooked vegetables), while daphnia and ostracods go for the smaller stuff--bacteria and micro-algae. Many critters hug the bottom where there's a lot of protozoa, bacteria, etc that they can feed on. So your focus should be there. You can use a turkey baster to pull debris off the bottom.

I've never had a problem with ostracods--so far--in my shrimp bowls. Every 2-3 weeks, I do 90% water changes, pull out excess snails, and tidy up the bowls. I refill the shrimp bowl with aquarium water, which is already conditioned with natural and protective DOC. I'm keeping only about 15-20 shrimp in the bowls. (The excess go into my guppy tanks to grow out.) In the past, I just let the shrimp overpopulate "willy-nilly" and eventually I lost the colony.


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