I've owned two. One a model reef tank fish the other semi and true to the 'with caution'. Both eradicated and/or managed my tanks aptasia problem. Meaning while the fish was in the tank there was little to no visible pest. Once the fish was removed it was noticeable.
Some notes:
1. Both are matted filefish (which I believe is Acreichthys tomentosus)
2. One was from LFS and unknown source
3. One was from Pacific East Aquaculture who only sells captive raised/bred - so it was from BIOTO and again Acreichthys tomentosus
4. First one was mature and probably a couple years old - hard to tell age when we don't ask or they don't offer it but I'd say 1 to 2 years a guess. Decent size and still grew in my tank
5. Second one was tiny - size of a quarter. Kept in a 5 gallon tank first for about a month then moved to my display
6. Both went after aptasia. Preferred spores and smaller size first. Medium second, and larger ones, well, it kept in check by eating tentacle's (more on this in a minute)
7. Great personality, always out, visible, changed color, ate all foods and continue to control aptasia
8. Both nipped at corals (soft, lps, and sps)
9. Both ate zoa's - I couldn't keep them
10. BIOTA one ate zoa's, small frogspawn frags, and duncan coral (remember the large aptasia and my comment on tentacle's? Duncan's have them and so I'm thinking maybe mine connected the dots - not sure just an observation because the base coral was left alone)
Probably sums it up. Owning one usually means you have a problem enough to warrant control. Shrimp are opportunistic feeders so typically second choice for me. I have seen them steal food from mouth type corals (elegance corals and bubble tip anemones). To the matted file fish one should consider the trade off and decide if it is an acceptable to mitigate the issue. They are great fish and do their respected job. Just known to nip corals. In fact there is a post from biota here and they noted their matted (which I used) filefish does indeed find duncan's tasteful ...
One interesting point worth noting. Goes for all of the "with caution" tagged fish. If the corals are mature enough such that they can outgrow the casual nipping then it becomes a moot point if they nip. Xenia, frogspawn, zoa's, or duncan's can out compete the drive by nips and it is no big deal. My first matted filefish was like this as it picked at my hammers but never hurt them. Whereas the 2nd one the corals are not mature enough so it caused issues (thus me returning to LFS).
Too long of a post - sorry. They work, they are great, be aware of some corals, and with-caution is for a reason. All the best!
