How do I moniter a new fish if I never see it?

[mike31154]

The little guy is out a little more this morning, nonchalantly cruising the right side pile of rocks as only a Mandarin can. Looks good, great colour and the small bit of tail fin he lost to the Damsel on day two is almost completely healed up. No other injuries apparent, but as I mentioned, if it is a male, once he starts growing larger and my big guy feels his territory is threatened, things could take a turn for the worse.