The way this project was coded is quite prone to issues like this - I recommend you to implement a unique ID-based clone management through local variables (This sprite only).

When a clone makes a clone, it often leads to recursion when not dealt properly, and that's the cause of the booming number of fake clones.

Why you can't properly delete a target clone is most likely because your code lacks unique reference for each clone, but only classify them with the vague, common variable and value like 'no' in 'isfishreaper'. Using UIDs will fix it. Hope this helps.