Subject: Juvenile Lyretail Hawkfishes (Cyprinocirrhites polyactis) are fighting the current, picking out bits of plankton while they swim. This is the only species of Hawkfish that venture in the open water to catch food. As for all Hawkfishes, these little ones do not have a swim bladder. That is why most Hawkfishes prefer to rest on things like coral branches. Due to the lack of a swim bladder swimming against the current is very difficult: it costs these fish an immense effort to maintain height/depth and speed.
Technique: It is best to position yourself at a right angle to the current when filming fish that are facing that particular current. Having a perpendicular shot of the fish allows you to show more details. However if you would position yourself at a 45° angle you would get a better depth perception.