Red Algae on Montipora, Frogspawn Bubbles, and Mantis Shrimp Question

[FlyinggFish]

Alright I have a 65 saltwater tank
Clean up crew
Cleaner shrimp
Blue Hippo Tang
Percula
Bangaii Cardinal
Sixline Wrasse
Engineer Goby
Purple firefish (MIA)
Red Wellsophyllia
Yellow Finger Gorgonian
Montipora Capricornis
Zoanthids
Star Polyps
Mushrooms

Alright I have a couple of questions and I hope somebody will be able to provide answers.
1. My purple firefish has gone missing. I did some research and found that they can hide for a while. Alright, I can deal with that. It's been 3 days and it has not been seen or does not come out to feed. Well I have a huge, and I mean huge, Wellsophylia Brain Coral. My Dad thinks that the brain coral ate it because since the fish has been missing the coral has been somewhat closed (like it was fed a Hefty meal). I usually feed it a good piece of silversides once a week. I really don't think that the brain coral could harm the fish enough AND have enough time to swallow it without the fish escaping
So my dad thinks the Brain Coral ate my firefish.
Note:I have screening over my tank that a fish cannot jump out of. I checked in my overflow and sump as well as on the floor and have not seen the firefish.
Now I am thinking that the firefish was eaten by a mantis shrimp. I have heard clicking, and it's not even clicking it's like knocking. I recently posted a thread saying that I heard the clicking come from my Bangaii Cardinal, which I saw the fish's mouth move and the sound was coming directly, or at least what seemed like, from the fish. But when I hear the knocking most of the time I feel that there is no way that that noise is coming from the fish. It seems so loud and like...up against a rock or something.
The couple of days that the fish has been missing the knocking was really bad. Which might be perhaps because the mantis shrimp was "punching" it to kill it.
Well, today when I got home I decided to look under the rock that the firefish always lives and hides under. Hoping to either expect a dead fish or a live one. NOTHING WAS UNDER THE ROCK! And that fish was ALWAYS under the rock.
Now I don't know what to think. Can you help?

And real quickly:
2. Last night when I got home from work I noticed a bubble floating around my tank. The bubble almost looked like a nice big bubble of bubble algae. I turned the lights on in the tank and to my surprise it was a bubble of frogspawn. Like a perfect bubble the size of a fingernail. It was just rolling around in the current and my Percula was going after it (kind of cute) and I didn't really worry about it. I was wondering if anybody would know why there would be a bubble of frogspawn. (And yes I have a frogspawn in the tank) And knowing how Engineer Gobies will go after anything to satisfy their curiosity he bit it! And swam quickly backwards. So I don't know what was going on with that frogspawn. Hope its not hurt and like shedding its tentacles or some part of the coral. Just wondering if anybody has seen this or knows why this happened with the frogspawn and its bubbles.
3. I purchased a beautiful Pink Montipora Capricornis a couple of weeks ago and noticed that it has red algae on it. Is that okay? Should I leave the algae on the coral? The algae is somewhat on the base of the coral not really where any pink is but it seems like it could be taking over. If I should remove it can I just kind of remove by rubbing it off with my hand or use a razor blade?

Thank you so very very much!

[es1887]

i have had my brain coral, a trac, eat a couple of fish. the fish were obviously not very healthy. a brain coral should not be able to snag a good healthy swimmer. a mandarin they might be able to get a little easier. i doubt that the brain got it. it could possibly be the mantis. those guys are great at hiding and if the fish hid in the rocks he would be quite a tasty morsel. a good way to get them out is to take the rock you susspect it in and dip it in fresh water for 60 sec to a min and he should come running out. does your frog spawn seem healthy. the only reason you would see that is if it has sloughed some of its tissue off, and it is not doing very well. the monti cap you should be able to squirt the algae off or you can simply rub it off gently. sorry to hear about the fish.

[FlyinggFish]

Yes my frogspawn seems very healthy, won't stop growing and it always nice and big in the day. I'll get a picture up in a couple minutes.

[FlyinggFish]

And if I did have a mantis shrimp...wouldn't it eat the blue legged crabs and snails first and THEN prey on fish?

[es1887]

yes that is most likely, but not necessarily what happened. i am sure you know this but fish do not just disappear from your tank if there is no way out. he could have died and then a hermit may have pulled it into a hole where you cannot see it. the brain coral could have eaten it but if that has happened the fish was either very weak or already dead. if you think you have a mantis it is better to deal with it now than waiting until another fish is gone. the brain can eat a fish that size very easily, but not a health one. feeding the brain coral once a week is a little excessive imo.

[FlyinggFish]

Alright. See it is very confusing. Whenever I am by the tank I know it is my Bangaii Cardinal making the noise; the what seems to be knocking on the glass noise. But then it seems like its so powerful that it isn't...but I'm so sure that it is.
I don't know whether to think mantis shrimp or Bangaii Cardinal. The fish is still missing. It seemed very healthy last time I saw it. And I do not have an increase in phosphates.