This is not a complete list of references, but rather some that you may find handy while learning reproduction assessments.
Grier et al 2009. The ovary, folliculogenesis, and oogenesis in teleosts.
Grier et al 2018 Oocyte Development and Staging in the Florida Bass, Micropterus floridanus (LeSueur, 1822), with Comments on the Evolution of Pelagic and Demersal Eggs in Bony Fishes. Reference has detailed images of oocyte morphology.
McMillen 2007 Female reproductive systems.
Wallace & Selman 1981 Cellular and dynamic aspects of oocyte growth in teleosts.
Schulz et al. 2009 Spermatogenesis in fish.
Sadovy & Shapiro 1987 Criteria for the diagnosis of hermaphroditism in fishes.
Sadovy & Domeier 2005 More Criteria for diagnosis of hermaphroditism in fishes.
Nakamura et al. 2005 Sex change in coral reef fish.
Atlas of fish histology and histopathology. Authors: Galit Sharon and Dina Zilberg.
Fish Histology Manual v4. Contributing authors: Sonia Mumford; Jerry Heidel; Charlie Smith; John Morrison; Beth MacConnell; Vicki Blazer.
4th Workshop on gonadal histology of fishes. Wyanski, D. M. and N. Brown-Peterson.
Education Guide: Special Stains and H & E Second Edition. Editors: Kumar, G. L. and J. A. Kiernan eds. This is a guide to stains that is not fish specific.
Thorsen & Kjesbu 2001. A rapid method for estimation of oocyte size and potential fecundity.
Arthur et al 2022 Alaskan Yelloweye Rockfish Fecundity Revealed through an Automated Egg Count and Digital Imagery Method.