Not my tank, this came up in another discussion on the internet with someone else and we spent a few hours of google fu trying to work out what it is. We're thinking some sort of Polyclad flatworm, it's a couple inches across. It could potentially be a Discodoris nudibranch too but I'm really leaning Polyclad. This is unfortunately the best/only media he has of the thing as he saw it once and never really saw it again in a 100g display.
He does have a few vermetid snails and he said that the population of those has been withering down a little bit, and he's lost a few snails recently, all pointing towards Polyclad. Sponges and corals he hasn't really had any losses recently.
(it's cruising under the hair algae in that video)
He's going to get some clams and try to bait it into a trap, so we'll see if he can get a better shot soonish.
He does have a few vermetid snails and he said that the population of those has been withering down a little bit, and he's lost a few snails recently, all pointing towards Polyclad. Sponges and corals he hasn't really had any losses recently.
(it's cruising under the hair algae in that video)
He's going to get some clams and try to bait it into a trap, so we'll see if he can get a better shot soonish.
