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Reproductive Anatomy
Fish Gonads (Testes / Ovaries)
Gonadae
The paired reproductive organs producing eggs (ovaries) or sperm (testes) - often enormous during spawning season.
Region: Trunk Universal in fish Unique to: all
📖 Overview
Fish gonads reach extraordinary proportions during spawning. Ocean sunfish ovaries produce 300 million eggs per spawn - the highest single fecundity of any vertebrate. Female sturgeon caviar accounts for up to 10-15% of body weight. Gonad development is tightly regulated by photoperiod and temperature via the endocrine axis.
🧬 Structure
Paired organs suspended by mesenteries in the coelomic cavity. Testes: sperm-producing tubules. Ovaries: follicle-lined sacs, hollow (teleost) or solid (chondrichthyan).
⚙️ Function
Gametogenesis (spermatogenesis or oogenesis), hormone production (androgens, estrogens), sexual behaviour signalling.
✨ Fun Fact
A female bluefin tuna gonad can weigh 25 kg at peak season - roughly 5% of her body mass - and produce over 10 million eggs per year.
🔗 Related Reproductive Structures