Aquaculture of ornamental fish is today a global industry worth several billion dollars. Nutritionally, ornamental fish are different from edible fish, so body color is more important in ornamental fish than meat production, and in terms of price, ornamental fish and edible fish are different. Aquaculturists strive to use food efficiently and at a reasonable price. Recently, efforts have been made to develop different diets for aquarium fish, and the use of invertebrates such as insects, Artemia, polychaetes, and worms has been studied. Polychaetes are among the live foods with high nutritional value that are approved for use in ornamental fish diets. Polychaetes (protein, fat, and carbohydrates) possess a biochemical composition that is suitable for feeding ornamental fish, resulting in better growth performance, survival, and color quality compared to concentrated diets. Ornamental fish farmers increasingly use polychaetes as sources of long-chain unsaturated fatty acids (such as docosahexaenoic acid, eicosapentaenoic acid, linoleic acid, and arachidonic acid) in order to improve growth performance, sexual maturity, and color quality. The importance of polychaetes as live food for ornamental fish is discussed in this promotional study.

Consideration of evenness indices (E1-E5) in the communities of polychaetes of Bihad. Doragh, Ghazaleh and Ghanam creeks (some embranchments of Mousa creek, Southwest of Iran) for a period of one year (Aug 1996-July 1997) has indicated the minimum value of the these indices in Gazaleh (E1=0.41, E2=0, 15, E3=0, 11, E4=0, 52 & E5=0, 35) and maximum (except E1) in Doragh (E2=0, 5, E3=0, 49, E4=0, 73 & E5=0.72), Maximum of E1 has observed in Bihad (E1=0.42), Because of nearness between N1 and N2 in Bihad and Doragh, their E1-E5 values were very similar together, By the reason of pollution, Gazaleh had very low dominance (N1=3, 7 & N2= 1, 93) and evenness and high diminace s.E1-E3 indices are very sensitive to the spices richness and E4 have a reverse relationship with individuals density, E5 a pproaches zero as a single species become dominant.

One of the most important marine ecologic phenomenon, is the study of animal community among the bed or benthic fauna. Macrobenthoses are the graet part of the benthic fauna, that are more biomasses than meiofauna and microfauna. To study polychaetes diversity of Mangroves, located in Khoore-Khooran, sampling was conducted on a bimonthly and carried out from December 2001 to October 2002. Bottom samples were collected by Van Veen grab (0.025 m2) at 6 station from 2 transect. In situ measurement of temperature, pH, O2 and salinity were carried out. A total of polychaetes were identified within study 32 families and 43 genera. Application of diversity and Richness, Evennes were studied and showed that the station A3 has the lowest evenness and the most individual, and station A1 has the middle pollution.

In aquaculture environments, organic enrichment significantly alters the chemical composition of pond sediments, leading to increased levels of organic matter, sulfur, and iron, alongside a reduction in pH. One promising approach to improve nutrient cycling and remediate contaminated sediments is the use of bioremediation through polychaetes. The selection of native species is crucial to mitigate the risks associated with introducing non-native, invasive species that may act as disease vectors or compete with native populations. This study, conducted from 2018 to 2020, aimed to identify and introduce polychaete species from the Persian Gulf with potential for bioremediation. A total of 41 sampling stations were selected across three provinces in the Iranian waters of the Persian Gulf—Hormozgan, Bushehr, and Khuzestan. Sediment samples were collected using a Van Veen grab sampler, washed with seawater, and analyzed for polychaete identification. The study identified 23 polychaete species from five families: Eunicidae (2 species), Capitellidae (3 species), Spionidae (5 species), Sabellidae (7 species), and Nereididae (6 species). The results highlight the potential of native polychaetes in bioremediation, enhancing the quality of aquatic substrates and contributing to the preservation of local ecosystems. These species play a vital role in the health and sustainability of ecosystems by degrading pollutants and improving environmental conditions. Thus, using native polychaetes for bioremediation can strengthen biodiversity and reduce the risks posed by non-native species in aquatic management and conservation.

For ecological study and species identification of Gorgan Bay (Bandargaz Coast) polychaetes, some seasonal samplings were carried out at depth of 1, 2 and 3 meter in 2004. During the study, only three species polychaetes were obtained that Streblospio gynobranchiata species was observed for the first time in the Caspian Sea. The oneway ANOVA analysis results (P<0.05) showed that this invasive worm has been able to be the dominant species of area polychaetes at all depths and in all seasons. Study of population dynamics and biomass of polychaetes indicated that at all depths, the maximum and minimum biomass was in spring and winter, respectively. Also, the maximum density was obtained at one meter, two meter and three meter in spring, autumn and summer, respectively and minimum density was observed in winter at all depths. The maximum and minimum of Diversity and Evenness Index was obtained in spring and winter, respectively while it was vice versa for Dominant Index.

The study aimed to assess temporal and spatial variations in the population of polychaetes, a significant invertebrate group in deep-sea ecosystems, across the northern waters of the Persian Gulf and the Oman Sea. Sampling occurred from fall 2018 to winter 2020, covering regions in Hormozgan, Bushehr, Sistan and Baluchestan, and Khuzestan. A total of 115 stations were surveyed, utilizing 0.1 square meters and a 500 μm sieve (repeated thrice) to collect bed sediments within the depth range of 12 to 90 meters. Within this study, 35 species/genus of polychaetes were identified in the waters of the Persian Gulf and the Oman Sea. Notably, Flabelligra sp., Manayunkia aestuarina, and Glycinde sp. exhibited the highest abundance, with Flabelligra sp. and M. aestuarina serving as indicator species in both regions. The provinces of Sistan and Baluchestan and Bushehr displayed the highest Shannon diversity and species richness, recording 3.592 and 6.998, respectively. Comparing these findings with prior reports revealed a reduction in the diversity of identified polychaete species in the Persian Gulf. This decline could stem from various factors such as habitat damage due to fishing equipment, and the incidence of contaminants. Continual research and database establishment for time series analysis could significantly aid researchers, authorities, and environmental advocates in comprehending the health status of the Persian Gulf and the Oman Sea. Such efforts would facilitate environmental monitoring and pollution prevention measures, contributing to the preservation of these ecosystems

The aim of this paper was to study monsoon effects on polychaetes population structure in subtidal area based on some biodiversity indices. Sediments sampling was carried out by grab van-veen from 12 subtidal stations in three time periods (pre-monsoon, monsoon and post-monsoon). The physical and chemical parameters were also recorded. Mean density of polychaetes were recorded 1101.2±614.3 ind/m2 (pre-monsoon), 428.9±316.2 ind/m2 (monsoon) and 588.8±313.3 ind/m2 (post-monsoon). Shanon diversity indices were 2.08, 1.63, 1.83 respectively. The Hill indices was reversed and showed highest number in monsoon season and minimum number in pre-monsoon. These results represented non-uniform polycheates distribution during pre-monsoon. Cluster analysis of each season showed that deep stations were in separate disturbances. During the summer monsoon, variations in environmental factors and bottom distractions affected the density and diversity of polychaetes and as a stressor reduced the diversity and density during the monsoon.

This research was carried out to compare diversity and distribution of polychaetes in western and eastern Jask creeks protected areas in Jask Port (Gulf of Oman), located in the East of Hormozgan province. Sampling of sediments was done seasonally from fall 2009 to summer 2010 by 0.04 m2 Van Veen Grab, in three stations including mouth, middle and end of each creek. A total of 72 sediment samples were taken from the stations. In this study, 20 species belonging to 16 families in the easten Jask area with a frequency of 9075 per m2 and 17 species belonging to 13 families in the western Jask area with a frequency of 4800 per m2 were identified. Polychaetes families were mainly consist of Nereididae, Owenidae, Capitellidae and Pilargidae. Ecological indices including Shannon - Wiener, Margalef and Simpson also were calculated. The average of Shannon index in different seasons and stations of eastern Jask (1.02±0.47) were higher than the western Jask (0.898±0.74). Correlation analysis between environmental factors and polychaetes showed that the abundance of polychaetes has a significant positive correlation with the temperature, oxygen, salinity and EC (P<0.05). Results of ANOVA revealed no significant differences between indices in different seasons (P>0.05). The results of Kruskal-Wallis test showed significant differences between the abundance of polychaetes in the eastern and western Jask (P<0.05). In additon, the results of this test indicated a significant difference in the abundance of polychaetes, between summer and fall and also between summer and winter, in both of Eastern and Western Jask (P<0.05).