Strange Occupants In A Turtle Tank

Question:

I have been keeping two yellow-bellied slider turtles since February.I clean the tank twice a week and it has an external  lter. Both turtles seem to be in good health but this week, I noticed that there were some small thread-like white worms on the glass of the tank.I don't know what they are, or if they are harmful to the turtles. Any advice would be appreciated.

Answer:

There are two likely candidates. Firstly, it could be planaria. These  atworms look more like miniature slugs though, rather than true worms, and they are tiny, averaging about 3mm (0.1in) long. They usually become more numerous after dark, emerging from their hiding places at this stage.

The other possibility is that these unwanted tank occupants are free-living roundworms (nematodes). They are signi cantly larger than planaria, growing up to about 20mm (0.8in) and their swimming action is just like that of a worm in water. They feed on detritus - uneaten food and faecal matter - in the tank, and so often congregate in large numbers in the  lter where debris of this type is trapped.

The good news is that neither of these creatures represents any threat to your turtles. They were probably introduced to the tank in the gravel. Unfortunately however, short of stripping down the entire tank, disposing of the gravel and replacing the  lter components, there will be no way of getting rid of them safely. But you can control their numbers by feeding the turtles in separate quarters, so uneaten food does not accumulate in the main tank, because they will multiply very rapidly under favourable conditions, where they have access to plenty of food.