I would rehome that shark asap. I had one in my planted tank about 2 years ago. He was great for the first 9 months or so, then went nuts ant started killing everything. Keep that water clean so the other fish can recover. What is the current tank temp? You may want to turn it up a little as well.
No, those are not my husbands tanks.
RCS, mosses, and crypt.
46 Bow Front Planted
Eheim 2217, 2-39wt T5 bulbs (6700k)
Onion plant, amazon sword, red lotus, christmas moss, guppy grass, and crypt lutea.7 pristella tetras, 9 cardinal tetras, 2 Otocinclus, 1 patty, 3 ghost shrimp, and several cherry shrimp.
All Male Hap, Peocock, and Mumba Cichlids.