See figure in attached file and try to link this distribution to the process of continental drift.

In "Communication in Fishes" 2006 vol 2 Peter Moller who was one of editors had added to this figure note about the existence of Asian weakly electric fish -see page 582. Now we've record electric discharges in 2 species of Asian Siluridae and 3 species of Asian Claridae. And in Giant Chineese salamander/

Here is an interesting article:

Genomic basis for the convergent evolution of electric organs

Jason R. Gallant et al., 2014

Science 27 Jun 2014: Vol. 344, Issue 6191, pp. 1522-1525 DOI: 10.1126/science.1254432

Abstract

Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs.

Hi Vladimir!

In the attached file you have an excellent review on the diversity and evolution of the discharge of the electric organ in fish by Dr. W. Crampton.

I hope it helps you.

Best regards,

Nonato

Thank you very much. It's really good review.