This fish might be a goby. It might be something else. It might be defending its burrow, it might be advertising for a mate. If it is advertising for a mate, it might decide to be either male or female, or it might decide to sneak into someone else’s mating session and provide a contribution. Frankly, there is too much uncertainty involving this fish and it should be thrown back. (Though if it’s a frillfin goby, it might jump back, so check for that first.)