Fish Reproduction
Animal Breeding
Pensacola Jr College
Female Fish Repro
Tract
w Ovaries compact and hollow
w Eggs usually shed into ovarian
cavity continuous with gonaduct (fish oviduct)
Ovary in Fish
Females -
Specializations
w Agnathans:
No oviduct
Eggs shed into coelom, then
must travel to cloaca
w Chondrichthyans:
Eggs fertilized and embryos
develop in ovisac
Hagfish Ovary /
tract
Shark Egg Case
(mermaids purse)
Females -
Specializations
w Seahorses and pipefish:
Female has ovipositor
(copulatory organ)
Inject eggs into male
abdomen
w Live bearers (eg. guppies):
Eggs fertilized and embryo
develops in ovisac
Seahorses
Seahorse Eggs /
Embryos
Pregnant Female
Guppy w/ gravid patch
Male Fish Repro
Tract
w Sperm cells develop in
association with Sertoli cells
w Leydig cells produce
androgenic steroid hormones
w Sperm produced in:
Seminiferous tubules in bony
fish
Spermatic ampullae
(cavities) in sharks and agnathans
Testis types in
Fish
Males -
Specializations
w Agnathans:
Mature sperm released
directly into coelom
No sperm duct
Sperm exit through a pair of
genital pores in abdominal wall
w Gnathostomes:
Sperm ΰ epididymis ΰ sperm duct (carries urine
too)
Male Hagfish
ducts drain kidneys only
Males -
Specializations
w Chondrichthyans:
Paired claspers for
copulation
w Live-bearing bony fish:
Gonopodium (modified anal
fin) for copulation
w Most bony fish:
External fertilization
Sperm expelled = milt
Shark Claspers
Gonopodium - guppy
Repro Tracts -
Rays
Repro Tracts -
Lungfish
Repro Tracts -
Teleost Fishes
Fish Sex
Determination
w Genetics
w Environment
Genetic Sex
Determination
w Heterogametic sex = produces
2 kinds of gametes and determines offspring sex
Usually male in fishes
w Homogametic sex = produces
one kind of gamete
Usually female in fishes
Environmental Sex
Determination
w Males and females may be
distinct based on temperature etc.
w Others often begin as females
and become males later
w Some hermaphroditic
Aquaculture and
Fish Sex
w Male fish usually more
colorful, larger, etc.
w Aquaculturists often attempt
to produce all male populations
YY males are viable and
produce all male offpring
w Case study: Channel Catfish
Types of
Egg-Layers
w Egg scatterers
w Egg-buryers
w Egg-depositors
w Mouth-brooders
w Nest-builders
Egg scatterer:
goldfish
Egg-buryer:
killifish
Egg-depositor:
cichlids
Mouth-brooder:
betta
Nest-builder:
gourami
Female Fish
Reproductive Cycle
w Oocyte development
Body size dependent
Not hormonal
w Vitellogenesis
Longest period
Nutritionally dependent
Female Fish Cycle
(contd)
w Oocyte maturation
Water uptake
w Spawning
Environment/courtship
triggers
Can induce with carp
pituitary extract or HCG
w Recovery
Die or recover and return to
vitellogenesis