Posted by beth on 12 Jan, 2019
Formalin baths are typically used for the treatment of brooklynella and black ich.
In a separate dedicated container, fill with water from your display. Use a 37% formaldehyde solution (brand name Formalin sold in the hobby) at 20 drops for each gal of water.
Be sure to aerate the bath water using a small pump that is dedicated for use in treating fish diseases.
Place infected fish in the bathe for 45 minutes, every other day, 3-5 treatments.
Warning: This is a toxic medication so don’t overdose. When finished with the bath, safely discard the bath water. Do not use the same water for subsequent treatments. Take care not to have direct contact with the formalin.