Is it forbidden to keep ornamental fish, and was the dog created from the filth of the place where Iblis and Adam (peace be upon them) quarreled?

There is no harm in owning permissible animals, provided they are not neglected. The Companions did so, and this is indicated by the Prophet's (peace be upon him) saying: "For every wet liver, there is a reward." However, animals that are forbidden to own, such as dogs and pigs, are not permissible to possess. Islam preceded others in defining the rights of creatures, and placed human rights at the forefront, such as sponsoring orphans. Based on this, it is permissible to own ornamental fish, with proper care. And Allah knows best.

As for the creation of dogs, there is no specific particularity to it unless there is evidence, and Allah knows best. Regarding Iblis, he disobeyed Allah's command to prostrate to Adam and misled him, and there was no filth involved. As for knowledge that is not beneficial, like delving into the creation of dogs, the Quran turns away from it to focus the Muslim on beneficial knowledge.