Whichever conditioner you decide upon, make sure you read the ingredients very carefully and avoid those with Aloe Vera, Tea Tree and any other aromatherapy type ingredient.
The bottles will state that these ingredients will help stressed fish....when infact they build up over time and fatally damage the labrynth organ in fish such as Gourami and Betta and slowly suffocate other fish by blocking the gills.
They do not disolve in water nor do they leave the water during the water changes....they sit there and each time they are used, the build up increases.