Got the tank water sorted- I thought-. But I have two ranchu sitting on or near the bottom mostly and occasionally making mad dashes flicking/rubbing gravel and tank sides. They have no other obvious signs of disease or parasites. WATER. Ammonia will not go below 0.25ppm but I assumed that it was NON toxic ammonia as I had added an ammo Lock product 2 weeks ago. ( This has stayed at .0.25 both before and after 60% water change) I have bought an ammonia alert but its not reading yet. Nitrite =0 Nitrate= 5ppm PH= 7.4 5 days API Pimafix anti fungal /mild anti bacterial. 60% water change still no change in behaviour. All I can think of now is Gill Flukes but need the opinions of yourselves before I do a treatment for this.