Juvenile fish Deaths

[PaulPerger]

I have had two juvenile fish die in the past few months. A Clown and a yellow tang. Both wedged themselves into rocks and could not get out.

Is this normal for juvies?

 

[eatbreakfast]

How big of a tank? What tankmates? What was the feeding regimen? How old is the system?

 

[PaulPerger]

It is my holding tank. Basically a BB QT tank with a few rocks. It is a 20 gallon long. Tankmates include a small clean up crew of snails and blue legged hermit crabs. The clown was one of two clowns at the time and about 3/4 of an inch long. The tang was about the size of a poker chip and it was him and a few chromis. Tank is fed twice per day, a varied diet of pellets, flakes and frozen misys. It has been up and running about 3 months now.

Parameters:
Temp - 79
pH - 7.8
Ammonia - 0
Nitrite - 0.25
Nitrate - 20
Phosphate - 0.01
Salinity - 1.025
Alk - 9
Calcium - 550
Magnesium 1340