Originally Posted by
Iminit
Lots going on and great advice already. I definitely see hith on your discus. The scar on the kobolt could be a few things. I’d guess it cut itself on that driftwood darting across the tank. The loach may have been taking advantage of the open wound. I’ve kept loaches with discus and never seen them go after the slime. Bn plecos is a different story. They can have a taste for discus slime and would put a hole in your fish like that. I had it happen years ago. Discus was going crazy trying to get the bn off. Cameras a great idea. I do have them on my tanks. Next as said your way under on your water changes. I’ve got the same tank 13 discus planted and I do 3 50% a week. Now you should be doing 50% daily. Also that tank won’t be big enough for the loaches and discus. Loaches can get to 10-14”. Will take years but they will grow. They are also much more aggressive at getting food.
Have your nitrates always been high out of the tap? What kind of filtration on the tank?