What is the ruling on eating fish that feed on fodder containing pig residues, and what is the ruling on dealing with this fodder in the study of fish farming?

If swine waste is chemically treated until it transforms into another component different from the original component, then this treatment is purifying.

Accordingly, there are two cases:

1. If swine waste is introduced into animal feed compounds after its transformation, then the feed is pure, and it is permissible to sell it, feed fish with it, and eat fish that have been fed with it, unless there is harm in eating them.

2. If swine waste is introduced into the compound before its transformation, then if it was wet, the compound might become impure. If it was solid, the impurity does not extend beyond the amount of the waste. In both cases, the feed is impure, and it is not permissible to sell it or feed fish with it.

As for the ruling on eating fish that have been fed with impure feed, it is not forbidden unless most of their diet consists of that impure waste, or if the effect of that waste appears in their flesh. In such a case, it is not permissible to eat them, as a matter of precaution, until they are rid of the effects of the impurity by feeding them with pure feed.