What you are talking about doing is called Aquaponics. Its definitely a cool system when it works well. Talapia fish are a very common fish used in this type of gardening.
TBH though as far as I know nobody has ever done scientific testing on aquaponics and cannabis to see if any fish can create the perfect ratios with their poop. I always wanted to try it myself. You would need two tanks though one for veg and one for flower. Which would require different types of fish in each.
But generally fish poop is mostly nitrogen. So for veg it would be good. However one tiny fish might not be enough poop for your plant.
TBH though as far as I know nobody has ever done scientific testing on aquaponics and cannabis to see if any fish can create the perfect ratios with their poop. I always wanted to try it myself. You would need two tanks though one for veg and one for flower. Which would require different types of fish in each.
But generally fish poop is mostly nitrogen. So for veg it would be good. However one tiny fish might not be enough poop for your plant.