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Table 4 Classification of maturity stages for males B. altianalis

From: Optimizing selection of sexually mature Barbus altianalis for induced spawning: determination of size at sexual maturity of populations from Lake Edward and Upper Victoria Nile in Uganda

Stages Description
Stage I: Immature  
Strand-like Y-shaped gonad and transparent. This stage is dominated by spermatogonia only
Stage II: Developing Easily distinguishable as males and off-white colored gonads. The majority of the cells are spermatogonia, and spermatocytes but occasionally few groups of spermatids and very few spermatozoa are observed
Stage III: Spawning capable Large gonads, off-white coloration; dominated by lobules filled with spermatozoa
Stage IV: Regressed  
Reduced in size with bloody perches. Other portions still look off-white. Microscopically they are large empty spaces with residual spermatozoa. However other portions may still have some viable spermatozoa.
Stage V: Regenerating  
Further reduced in size with pale reddish coloration. This stage largely contains parked spermatogonia with reduced spaces containing very few residual spermatozoa.