Fish tail regeneration

[Muzej]

Dear friends, 
can you recommend to me some sources, or references about occuring of abnormal tail in group of fishes, tail regeneration et similar. 
I noticed some unusual forms of fish tails and I am interested in references related to Perciformes for example. 

I am interested if this occured frequently in group of fishes, 
or not. Maybe I noticed something interesting for my MSc thesis. 
Thank you in advance. 

Best wishes to all of you! 

Boze Kokan 
Natural History Museum Split
Croatia 
Europe