From The Aquarium Wiki
Probiotics are good bacteria or yeasts that live in the digestive tract of you and your fish.
Recently the problem of fancy goldfish getting constipated and having trouble digesting the processed food we feed them has caused a few aquarists to add probiotics to their food.
You can buy probiotics in capsule form and this is a powder. You mix the powder with other fish food and mix them into a gel. You don't put the probiotics straight into the water!
When to use Probiotics?
- After any antibiotic treatment has been used.
- When the fish shows long stringy or stumpy tracts of waste material.
Types of bacteria
- Lactobacillus Acidophilus La5
- Bifidobacterium Bb12