Suit yourself, but I'm telling you I've done it in 40 gallons with HOB filter and a heater (plus a half dozen PVC elbows). I have a Tomini Tang, Coral Beauty Angel, Royal Grama, Six Line Wrasse, Yellow Corris Wrasse, Bicolor Blenny, and a few Orange Tail Damsels. Get an ammonia alert placard, feed lightly and change water as needed to maintain water quality.
Do a quick search on freshwater dip for marine fish and read a little. It takes about 15 minutes and you will be able to see if any flukes fall off (do it in a white bucket so it's easier to see if anything parasites fall to the bottom).