I’ve had a pair of clownfish for a month now and one of them continues to lay in the sand bed in the exact same spot all the time. Clownfish swims swims to eat and seems to be healthy other than that. My first thought was ich or velvet but I’m not so sure since all my other fish seem happy and healthy. Parameters are all good and stable. I’m still new to reefing and am unsure of what to do. Any advice?