• Spawning can be pair spawning (one male, one female) or group spawning (one male with multiple females).

• Fertilization is external. Females lay their eggs into open waters and males fertilize the eggs by releasing their sperms in their vicinity.

Relationships & Adaptations of a Parrotfish. (2020, November 19). Pets on Mom.com. https://animals.mom.com/relationships-adaptations-parrotfish-8336.html

Some species of parrotfish are hermaphrodite protogeny. Rivulated parrotfish for example go through the early stages of life as females, between the length range of 126-270mm. between the lengths 246-350mm, they turn into males. Female rivulated parrotfish reach sexual maturity at 2 years and undergo a period of sex change to male sex when they are 3 years old

Tuwo, A., Tresnati, J., Huda, N., Yasir, I., Rahmani, P. Y., & Aprianto, R. (2021). Reproductive strategy of rivulated parrotfish Scarus rivulatus Valenciennes, 1840. IOP Conference Series: Earth and Environmental Science, 763(1), 012002. https://doi.org/10.1088/1755-1315/763/1/012002

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Mate Selection

Among other parrotfish species such as bumphead parrotfish mate in time with the lunar cycle, possible to coincide their breeding events with tides to ensure their eggs are pushed out to open ocean and away from predators. During breeding events, males position themselves at designated territories and court the females by swimming in bursts and temporarily changing colour. Females, in response, turn their faces white and the pair take their affair near the surface where they release their eggs for fertilization.

Dell’Amore, C. (2015, March 8). Head-Bashing and Other Mating Secrets of Giant Parrotfish. Animals. https://www.nationalgeographic.com/animals/article/150308-parrotfish-science-oceans-animals-mating-moons

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Hays, J. (2023). Parrotfishes: Characteristics, Behavior, Mucus and Sand-Creating Teeth | Sea Life, Islands and Oceania — Facts and Details. Factsanddetails.com. https://ioa.factsanddetails.com/article/entry-126.html

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two types of pelagic eggs:

• isolated eggs (majority)

• agglutinated eggs (lophiidae): eggs form a mass and move together

reference:

IASRI. (n.d.). Fish eggs and their characteristics. eCourses Online. http://ecoursesonline.iasri.res.in/mod/page/view.php?id=38791

• usually have a thick and more complex chorion and is more resistable to damage

• usually has a higher lipid content

• develop slowly, can take more than a month to hatch

• type of eggs produce do not link between habitat and species of fish (pelagic fish can produce demersal eggs, demersal fish can produce pelagic eggs etc.)

two types of demersal eggs:

• adhesive: (exocoetidae, gobiidae) they are adhesive to substratum using adhesive egg membranes / filaments

• non-adhesive: (salmonidae)

some examples of species with demersal eggs:

deep sea wolf herring (demersal fish)

references:

Blaxter, J. H. S., & Hempel, G. (1988). Buoyancy, egg size and predation in marine fish eggs. Sarsia, 73(1), 13-21. https://www.tandfonline.com/doi/pdf/10.1080/00364827.1988.10420671#:~:text=Demersal%20eggs%20usually%20have%20a,a%20relatively%20high%20lipid%20content.

IASRI. (n.d.). Fish eggs and their characteristics. eCourses Online. http://ecoursesonline.iasri.res.in/mod/page/view.php?id=38791

• most species have spawning seasons or exhibit seasonal cycles in the production of gametes during specific seasons of the year. this is usually called breeding season for species

• before spawning, female species usually have maturity stages before the release of eggs for fertilisation. stages include resting phase, early maturing phase, advanced maturing phase, mature / prespawning phase, spawning phase and spent phase.

reference:

The Fish Site. (n.d.). Maturation and spawning in fish. Retrieved from https://thefishsite.com/articles/maturation-and-spawning-in-fish

• favoured in situations where if large females in a small group changes sex into a large dominant male to control reproductive access to females

reference:

Todd, E. V., Liu, H., Muncaster, S., & Gemmell, N. J. (2016). Bending genders: The biology of natural sex change in fish. BioEssays, 38(11), 1117–1135. https://pmc.ncbi.nlm.nih.gov/articles/PMC5567342/#:~:text=Unique%20among%20vertebrates1%2C%20sex,large%20dominant%20males%20(protogyny).

• this happens in small groups when the largest male would change sex to become the largest female to produce more eggs

reference:

ScienceDirect. (n.d.). Protandry. Retrieved from https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/protandry

• The sex of the fish is determined by genetics (genetic)

• Sex can be determined by environmental factors such as water temperature, pH, and oxygen concentration (environmental)

• Sex is determined by social factors like the disappearance of a male or female from a group (social)

• Parrotfish begin as tiny, floating eggs in the water column. These eggs are fertilized externally during spawning events.

• They hatch into larvae within a few days, depending on environmental conditions like temperature.

Larval Stage

• Newly hatched larvae are planktonic, drifting with ocean currents.

• They feed on microscopic plankton and develop rapidly.

• This stage lasts a few weeks before they settle on coral reefs.

Juvenile Stage

• After settling on a reef, the young parrotfish develop bright colors.

• They begin grazing on algae, an essential behavior that helps maintain coral reef health.

• Juveniles are often different in color from adults and may resemble different species.

Initial Phase

• Most parrotfish start life as females (protogynous hermaphroditism). They will continue growing and reproducing as females.

• Some species may remain female their entire lives. (etc. Redband parrotfish)

Terminal Phase

• Some dominant females transform into males, displaying dramatic color changes.

• These males are larger, more vibrantly colored, and defend territories or harems of females.

• This change is influenced by social and environmental factors.

Vedantu. (n.d.). Parrotfish. VEDANTU. https://www.vedantu.com/animal/parrot-fish

Background information. (n.d.). The Parrot Fish. https://parrotfishinformation.weebly.com/background-information.html#:~:text=The%20initial%20phase%20is%20when%20a%20parrot%20fish,They%20also%20will%20experience%20the%20greatest%20reproductive%20success.

Simultaneous:

• Fish have both male and female reproductive organs at the same time

• Can alternate between male and female roles during their spawning period

Sequential:

• Fish start out as one sex and change to the other later in life

• Protandrous - fish develop as male first then change to female

• Protogynous - fish develop as female first then change to male

• Allows the developing ambryo to absorb nutrients directly from the mother's ovary in certain species of viviparous fish, essentially providing nourishment to the fetus during gestation

• Fishes with pseudoplacenta have a higher likelihood of exhibiting superfetation, which is the ability to gestate multiple broods at different development stages

• Allows for the exchange of nutrients and oxygen