Are planaria inevitable?

A few weeks ago I posted in the recent "bugs" thread about how I hate planaria and how every new plant gets a soak in fendbendazole before I put it into a tank. I didn't see any planaria for a long time...until now. There are some tiny ones crawling on the glass again.

Two possibilities of how they got in:
- they were never exterminated in the first place (everything was boiled or soaked in Panacur at that time)
- they got in with food (earthworms, frozen bloodworms, some other frozen food)

Does anyone know if they can come with the food? Some articles on the internet seem to suggest they live everywhere so you can introduce them on earthworms, for example. Is this possible?

I am about to start a new tank so I am wondering if I should:
- use material from the old one for it (planaria including)
- rip everything apart and start again in the old tank while starting the new one from scratch. The main question is, naturally, is it worth it - or will the nasty worms get in anyway.
- medicate the tank with low dose fenbendazole - I could temporarily move the newts out but I'm not sure what the medication does to the tank's useful bacteria.

Thanks for your help!

hmm..are they really a problem though? We not leave them where they are - maybe the population will regulate itself eventually?

The only harm I think that these do is to eat newt eggs and (perhaps) newly hatched larvae if they are a bit premature. Otherwise, they seem to be not a problem, although they frustrate the newts when they try to eat a rubbery, amorphous blob (reminds of me Wompus Galumpus)...!

I have had them in with bloodworm, both alive and frozen, although I'm not sure they can survive being frozen. Could you have transferred them on hands/equipment from other sources?

I think a small number are inevitable, but sometimes they reach very large numbers. All of my tanks have a few in them, but I would have to actively search to find any. Other people seem to get plagues of them, so I suppose it depends on individual tank conditions.

Perhaps going over top a bare-bottom tank where you can siphon out more debris and planaria more easily would help...

It is not a real infestation at the moment - the planaria are tiny and there aren't that many (visible). I have increased water changes and cleaning a bit for now. If they can get in with food then it's really not worth undertaking any major clean up I suppose. They can't have come on anything else I think - I am super careful because I hate planaria so much.

I did start with bare bottom tanks but have sand now (with plants in it) and really like it. I would like to put a bit of soil under the sand in the new tank.

One thing I forgot to mention is that I recently increased aeration in the tank and replaced the light tube. This seems to have affected a few things - fewer visible ostracods, brown algae covered everything (normally the ostracods would be eating it...) and there is also lots more hair algae. I wonder if the planaria becoming visible again are also some sort of reaction to this.

The whole situation in this tank is really bothering me - but I think there wasn't enough aeration in the first place so I'm reluctant to just switch the air stone off again. Will these problems pass?

The tank will tend towards an equilibrium if you maintain a regular schedule. I wouldn´t worry about planaria as long as you don´t see large numbers or large individuals. You may want to introduce some kind of competing organism like shrimp or Asellus or something, it may work.

Planaria can be tricky as their are different kinds. Personally, I have never had the egg and larvae eating type (except on purpose as their regenerative powers are really cool to observe).
I used to get the harmless, but disgustingly numerous type. I they do depopulate and often altogether go extinct as a tank ages. I find that the only way to manually get rid of them is to do a complete tear down and soak/wash everything with a quicklime and water solution. Even then, they will be back as they often hitch rides on the caudates themselves.

The type I get, the very small all white ones, are eaten by ramshorn snails. But trading snails for planaria may not be what you were looking for.

Thanks for your answers, everyone. It seems that trying to have a completely planaria free tank might be too hard to achieve. I am pretty sure I did everything possible to get rid of them and to not introduce them again....and yet they're back. They are small and seem harmless and not very numerous, so it would probably be a good idea to ignore them for now. I'll see if more cleaning helps.