Got the gas tank out, now the aerators?

Drained what was left of the gas tank and was able to get it out. Now I want to replace the bilge pump and two aerators. The bilge is straight forward but I am not sure about the aerators. How do you go about disconnecting them from their locations? One is through the hull and the other is through the livewell. This is in a 98 21 XD. What is holding them in place, is there a screw or something? It is really hard to see exactly what is going on in there and I don't want to damage the boat in any way.

Look real close there should be a plastic nut on either one side or both, it goes on the threaded tube that feeds into the live well or through the hull.. Be sure and use either 4200 or marine silicone to re seal the new through hull fittings.. Smear some on the wood inside the hole all around then put a generous amount on the pipe going through the hull..