I have an outbreak of red/brown flatworms which while not really threatening the corals is concerning and I want to get it under control. For varous reasons I am not keen on freshwater bathing, sucking them out etc and what I really want is a predator.

The options seem to be either a mandarin fish or a six line wrass. Has anyone any experience of introducing these fish to clear up flatworms?

Alternatively, has anyone got any top tips to clear them up? I have tried increased flow with little success.

Thanks in advance for any help

I've been looking into this myself ( http://www.fishkeeping.co.uk/modules/ ... p?topic_id=22814&forum=21 )
Most expert advice I've read suggests leaving the flatworms to blow themselves out. At the same time almost everyone that's had a problem has added a predator or changed their system somehow.

The predator option is very tempting but I have read very mixed reports. I'm concerned that the Manderin may die of nutrient deficiency over the long term. Most dragonets don't do well in captivity.

The Sixline Wrasse is a much safer option and the fourline wrasse is also said to eat flatworm. Not every one who bought one had positive results though.

No firstline experience yet - but if you find out first, let me know!

Thanks that is interesting.

I am in two minds about the mandarin - they are really interesting fish and my now 85kgs of live rock is literally crawling with suitable food. The flip side is though I would hate for one to starve to death in my tank. Has anyone successfully kept one for a decent length of time or for that matter the wrasse?

Although I said in my previous post increased flow has had limited success, the flatworms do not like it. I keep on aiming my powerheads at rock covered in the flatworms and they clear/blow off it within 20 mins. The problem is they just seem to regroup somewhere else hours later where the flow is less. I am hoping I am doing some damage to their numbers by doing this though.

85kg of live rock !?! Your tank must be huge.

I've got about 100gals and 40kg of rock or there abouts plus a refugium so I suspect there would normally be plenty of food but the flatworms I have seem to decimate the copepod colony.

Hodgey - I have kept a six line wrasse for about 5 years now, great fish! But I did not get him to decimate a flatworm population, so I don't know if it will work.

On the subject of a mandarin, I know that a lot of people who keep them or similar fish that are hard to maintain (blue cheek gobies etc) keep an upturned plant pot somewhere behind the rock structure. If it has small holes in it - the copeopods can breed and enter in and out without being preyed upon. Never done it myself, but just a thought.............

I have reserved a lovely sixline wrasse I spotted last night at the lfs. Collect on Friday and he'll go into quarantine for at least a month. He looks to be in perfect health, as does everything in his tank but the store do have some very ropey looking Regal Tangs and a Porcupine Puffer with what looks a lot like white spot (but they think is damage from a lionfish) ...

Great you will have to let me know how you go on. I am tempted to go out and buy one myself but I currently have a goby in my Q'tne tank who needs to stay there for a couple of weeks before i transfer him to my main tank.

BTW my tank is also 100 gals but I guess I have lots of rock in it. I have not been especially efficient I suppose and only live rock is in the tank nothing else such as egg crate or whatever. My water quality is fantastic though so it cant be doing any harm.


I would be grateful for updates on your war against the flatworms.

i have a massive flatworm ploblem i hate them! i also have a manderin he desnt eat flatworm! so i now have a silver belly bannana wrass who eats baby flatworm but not ennough to really notice the diffrence. watch the 6 line as they can be aggressive and be prepaired to think you've lost him as quick as a flash they bury themselves in the sand lol takes a while for them to settle in! really pleased with the wrasse tho great fish! its still possible to get flatworm exit but it kills all podlife in your tank not just the flatworm which is why ive not used it, wouldnt have been a problem untill i introduced the manderin so catch 22 really

Good news flat worm fans I have discovered what looks like at least a temporary solution. He is called a Blue Velvet Slug. I went into my local fish shop asking about the 6line wrasse but the guy pointed these things out so I bought one immediately. He is quite pretty actually too - the best looking slug I have ever seen in fact.

There are snags:

- they eat the worms to near extinction but when they finish eating them they die due to starvation. (I am not currently worried about this at the moment due to the sheer scale of my flatworm problem)
- they are supposedly difficult to keep (mine has been in over a week and seems fine)
- they are sensitive to nitrate etc (Not a problem in my tank at the mo)


For all this I am willing to take the risks and my little chap is currently happily slithering over my rocks chomping the flatworms - brilliant!



http://www.liveaquaria.com/product/pr ... =497+524+2198&pcatid=2198

Good call Hodgey. You seem to know exactly what you've bought there both the benefits and pitfalls. I decided against Nudibranch for flatworm control as I have a porcupine puffer...

My little 6 line has been healthy as an ox in the quarantine for 2 weeks now so along with various other considerations I've decided to give him the green light and moved him to the display tank this morning. He's busy exploring the rock work.