BTA short tentacles

[sfboarders]

Recently I've noticed that the tentacles on my purple/green tip BTA has shorter tentacles compared to when I bought it. It currently hosts 2 of my clowns but the female is in there all the time. I feed it Rod's and PE Mysis every other day and it seems to be eating well. Water parameters are ok too. It's been in the same spot since it moved there which was almost a year ago.

nitrate - < 5
nitrite - 0
ammonia - 0
ph - 8.1
calcium - 410
alk - 10
mag - 1300