My first Salt

Welcome! The fish looks like a purple pseudochromis from the picture. Feisty little buggers. He looks a little over-fed though. There are alot of problems that can potentially occur with over feeding. Such as nuisance green hair algae. It can over take your tank very rapidly. Also your lionfish will eventually grow large enough(very quickly) and eat the pseudo, clown, they love shrimp, and anything small enough to fit in it's mouth. Also dragonets (mandarin gobies) require a special diet of copepods etc. that are usually raised in a refugium attached to your main system. As for the shark good luck. I wish you luck in this hobby and if you ever have Q's feel free to write.

 

Nice. I'd do some research on the goniopora (flowerpot). They are very difficult to keep. I bought one before doing any research and it has perished. Even some of the pros on 3reef have had difficulty.You'll learn that a little research saves alot of money. Do you have any live shrimp in your tank for the mandarin? Mysids or pods?

 

Yes green hair algae can, and looks like it is becoming a problem in your tank. Also, adding a refugium to your system will provide a safe haven for various natural food sources required for your mandarin. It also helps control phosphate, nitrate and is beneficial to your tank in many ways. There are many options for a refugium. Build one to meet your size requirements or buy a manufactured one. They even make hang on tank versions. Canister filters have a tendency to raise nitrates.known to kill . I have no mech or chem filtration in my system at all. I use a sump filled with live rock and a refugium.