In the present study a comparison of the otolith morphology of two species of parrotfish, family Scaridae, collected from the Red Sea coast of Egypt, is conducted to identify the most appropriate taxonomic characters that separate these species. Ontogenetic changes in the otoliths of the two scarid fishes become evident. In the otoliths of Chlorurus sordidus, the following characters are comparable in small-sized adult fishes: otolith width, otolith depth, mesial surface shape, lateral surface shape, shape of sulcus acusticus, column, rostrum and size of rostrum. The otoliths of young adults (GI) C. sordidus differ from the adult ones in 14 out of the 22 characteristics studied. In the otoliths of Hipposcarus harid, the following characters are comparable in small and large fish: otolith width, otolith depth, mesial and lateral surface shapes, shape of sulcus acusticus, rostrum and size of rostrum.

Age and growth of Agassiz's parrotfish Sparisoma frondosum captured off Brazil (Pernambuco) were estimated using sagittal otoliths from 251 specimens. Sex of each specimen was determined and showed that 130 specimens were females (13.1 to 36.8 cm TL) and 121 were males (17.5 to 36.6 cm TL). The otolith marginal increment analysis indicated a single translucent ring formed every year. Parameters of growth curves were derived for the von Bertalanffy (VBGF) and Gompertz models. Based on the Akaike information criterion (AIC), both models were suitable for describing the growth of this species. VBGF parameters were estimated for males L ∞ = 39.74 cm TL, K = 0.22, t 0 = −1.63 years, females L ∞ = 32.38 cm TL, K = 0.44; t 0 = −0.23 years; and for the sexes combined L ∞ = 33.66 cm TL, K = 0.41, t 0 = −0.27 years. The study showed that 55% of individuals were 3 and 4 years of age, with maximal age of 9 years. Mature females (>17.6 cm TL) accounted for 45% of the sample. The age at first maturity for females was 1.6 years. For males the size at first maturity was not determined as immature individuals were not present in the overall sample. Also, primary males (PM) and specimens with gonads undergoing sexual transition were not found. The age structure and growth parameters for S. frondosum are an important contribution to the assessment of the state of exploitation of this species.

Herbivory is one of the most important biological processes influencing coral reefs. In the highly diverse Indo-Pacific reef fish communities, different herbivores can have strikingly different functions. We investigated the extent of functional diversity among herbivorous parrotfish of the more species-depauperate Caribbean Sea. We carried out observations of seven species of parrotfish (Scarus taeniopterus, Sc. vetula, Sc. iserti, Sparisoma viride, Sp. aurofrenatum, Sp. rubripinne and Sp. chrysopterum) on four Barbadian coral reefs to collect information on foraging techniques, rates, and targets, and found marked interspecific variation. Species of the genus Scarus had higher foraging rates than those of the genus Sparisoma. Different species took varying amounts of live coral, turf algae and macroalgae. A functional categorization based first on foraging technique (contact or no contact with the substratum) and secondarily on the more conventional criterion of foraging target (macroalgae, turf algae and live coral) allowed us to classify Sc. taeniopterus and Sc. iserti as ‘scrapers’, Sp. aurofrenatum, Sp. rubripinne and Sp. chrysopterum as ‘grazers’, Sp. viride as a ‘bioeroder’ and Sc. vetula as a ‘bioeroder/scraper’. This functional group affiliation, together with species-specific foraging rates, allows us to predict the role of Caribbean parrotfish on major coral reef processes and their impact on coral reef benthic communities.