Something is eating my corals

[JasonD]

Over the last several months my zoanthids and mushrooms have been disappearing. Not whole colonies, just a few polyps here and there. I started moving the colonies from the display down into the sump and the polyps would stop disappearing. I have been closely observing for the usual zoanthid predators, but there are no signs. Plus when I move a colony the predator is not introduced to the sump. I do have a lot of potential predators in my system. Tangs, scarlet hermit crabs, blue legged hermit crabs, coral bandit shrimp, cleaner shrimp, 3 peppermint shrimp. A few weeks ago I caught the predator red handed. I saw one of my peppermint shrimp pulling the polyps off one of my prized Yuma mushrooms. I pulled the Yuma out of the display. My other red Yuma had already had the top picked off of it. It is recovering in my other system. I am not sure if this Yuma will make it. This is really sad because this green-yellow Yuma was nearly 4 inches across.

Well now that I had a pretty good suspect, I decided to build a trap. I did not see any other way to catch them. I did not want to pull apart a 120 gallon reef tank. Even if I pulled all the rock out, there was no guarantee I would even catch all the shrimp. I build a 2 litter pop bottle trap. I cut the top off the bottle and inverted it to serve as a one way entrance into the bottle. I baited it with some meaty food and placed it into the tank. Through out the evening I checked on the trap with a flashlight. There were tons of snails and hermits all around the bottle, but nothing inside. I woke up in the middle of the night and gave the trap one more check. At the entrance of the trap I spotted a 2” white crab (this was no hermit)!. I grabbed the bottle and turned it upright trying to snatch it. No luck, it got away. I put the trap back and waited and watch. The crab came back out. I tried to capture it, again no luck. This morning I checked on the trap again. There where two shrimp in the bottle. One was my cleaner shrimp and the other was one of the peppermint shrimp.

After seeing that other crab, I am wondering if the peppermint shrimp are to blame for the missing corals. I did see one eating a Yuma. Over the years, I have seen hermits and shrimp eat dieing coral tissue. I am wondering if the Yuma was dieing and that is why the shrimp was eating it. I would hate to get rid of my peppermint shrimp, if that huge crab is really the culprit. My peppermint shrimp are large and have become a nice vibrant red color (the coloration is probably from eating all those zoathids J)

Very long winded, sorry. Advice: Should I take the peppermint shrimp down the LFS? Should I catch the other crab first and give the peppermints another chance? Since I have been having so much trouble with just zoanthids and mushrooms, I set up a 40 gallon breeder tank in the garage. Almost all the colonies have been moved and are doing well. The predator does not seem to touch SPS and LPS. So another option is to convert my 120 gallon Display into a SPS dominated tank and forget about keeping zoanthids in there. I already have the 2x250 watt halides. The few SPS I do have are thriving through all of this. I am having a hard time getting excited about SPS. I just have not seen anything that rivals the colors of zoanthids (probably just my SPS ignorance). I do like my orange and neon green monti caps though.

The trap works good for shrimp. It does not work really well for crabs. The funnel part is too smooth and the crabs can’t climb up the sides. I am going to try to build a better crab trap and try again tonight.

Thanks,

Jason

 

[jsmkmavity]

good luck with the trap, hope it works soon. i would work on that and not worry about the shrimp for now.

 

[chris&barb]

from how you are describing you'r things are being eatin, i would guess your dealing with a Hermodice.

http://marinebio.org/species.asp?id=292

 

[redrooster]

Well I'm not sure what to do about your predator. I too have tons of stuff in my tank and it makes it hard to pin down the source of a problem some times. I recetnly introduced a copperband butterfly to get rid of a few aptasia's. Well he did that in short order, but now I think he may be eating zoo's.
Anyways what I wanted to tell you is there is SPS out there that is not only as nice, but is much more colorful than even yumas or top notch zoo's. It's just 1) Really hard to find 2) Difficult to keep (relatively to zoo's/shrooms) 3)expensive. It is easier to find if you are willing to buy online, but I never buy livestock unless I see it in person. Top notch SPS frags sell for $40-$80 and they are very small. Big high quality colonies can run $300-$1000 if you can find them at all. I had a friend who sold a 16" x 12" green cup coral that had been in captivity for over 10 years and he got $300 from a dealer for it. It wasn't even that colorful just huge. I introduced him to the dealer. In confidence the dealer told me he sold it later that day for $750.
Anyways you might be really suprised how nice Acro/Monti can be under the right lighting. I too have 2x250W halides but on a 75G. I recently bought 2 pieces of Acro from an LFS. One was yellow and one was red. Both were about 3" with 3 branches. ($40 each BTW so reasonable) The yellow glows green under my actinics, but still looks mostly yellow under the halides. The red piece is red under the halides, but glows blue under the actinics? Until this time I didn't know they could do that. Hell I didn't even know they would "glow" under actinics as they don't seem to do it at any of the LFS by me. Maybe the best part I've found is since they don't expand its easier to place them in your tank, and they don't need to be fragged as often. When I first got into reefing I was impatient and went with softies in part because they grew quickly. Now the I am constantly breaking up coral fights, my opinion on this trait has changed. Slow growth makes husbandry easier IMO.

 

[JasonD]

Very tempting to jump on the SPS bandwagon. We have a new LFS in my area. The owner is setting up an SPS tank soon. He says he has some premium stuff. I am looking forward to it.

Well I'm not sure what to do about your predator. I too have tons of stuff in my tank and it makes it hard to pin down the source of a problem some times. I recetnly introduced a copperband butterfly to get rid of a few aptasia's. Well he did that in short order, but now I think he may be eating zoo's.
Anyways what I wanted to tell you is there is SPS out there that is not only as nice, but is much more colorful than even yumas or top notch zoo's. It's just 1) Really hard to find 2) Difficult to keep (relatively to zoo's/shrooms) 3)expensive. It is easier to find if you are willing to buy online, but I never buy livestock unless I see it in person. Top notch SPS frags sell for $40-$80 and they are very small. Big high quality colonies can run $300-$1000 if you can find them at all. I had a friend who sold a 16" x 12" green cup coral that had been in captivity for over 10 years and he got $300 from a dealer for it. It wasn't even that colorful just huge. I introduced him to the dealer. In confidence the dealer told me he sold it later that day for $750.
Anyways you might be really suprised how nice Acro/Monti can be under the right lighting. I too have 2x250W halides but on a 75G. I recently bought 2 pieces of Acro from an LFS. One was yellow and one was red. Both were about 3" with 3 branches. ($40 each BTW so reasonable) The yellow glows green under my actinics, but still looks mostly yellow under the halides. The red piece is red under the halides, but glows blue under the actinics? Until this time I didn't know they could do that. Hell I didn't even know they would "glow" under actinics as they don't seem to do it at any of the LFS by me. Maybe the best part I've found is since they don't expand its easier to place them in your tank, and they don't need to be fragged as often. When I first got into reefing I was impatient and went with softies in part because they grew quickly. Now the I am constantly breaking up coral fights, my opinion on this trait has changed. Slow growth makes husbandry easier IMO.

 

[aquarookie]

JasonD, I do not advocate that you get rid of your zoas and yumas, but IF you do, I want them all!

 

[mfinn]

Jason, I would suspect the crab is doing most of the damage.
I have lost stuff like that and not had any shrimp or fish in the tank. But caught crabs.
If that trap doesn't work for you, try a small jar, like a baby food jar. Bait that and leave it upright on the bottm next to some rocks. May take a week or so.

 

[JasonD]

I will give that a shot. Thanks.

Jason, I would suspect the crab is doing most of the damage.
I have lost stuff like that and not had any shrimp or fish in the tank. But caught crabs.
If that trap doesn't work for you, try a small jar, like a baby food jar. Bait that and leave it upright on the bottm next to some rocks. May take a week or so.