I had mine do the same thing when they first started to host. They eventually quit. There was no harm done. Be forewarned, I had one BTA three years ago and now I have three. Know anybody who wants one?
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Since 02-04, 125 gal with 150 lbs of live rock, 100 lbs of live sand, 2-175 wattt MH, 4-65 watt acintic compacts, Coralife skimmer, 20 gal sump/refugium, 25 watt UV, Fish 1 Royal Tang, 2- Hawiian Tangs, 1-Flame Angel, 1-Emperor Angel, 2-Watchman Gobies, 1-Marron Clown, 1-Percula Clown , 1-Manderan goby, 1-6 line wrass, 6 stars, 1- sand siffting , 1-royal gramma. Corals 1-bubble coral, 3-bubble anemone (was one it split), White Xenia, button polyps, mushrooms, zoos. | 
Clownfish hosting BTA question. 
I am so excited!... anyway.. I noticed they are sucking the tenticles wether it be the tips or half way along the tenticle and sucking on it.. is this normal? 
