Aquatic larvae of chironomid midge, CHIRONOMUS RIPARIUS Meigen, are one of the richest diets in fish rearing systems. The quantity and quality of food used to rearing these larvae, affect this developmental stage. This study was conducted to determine the effect of different diets (chicken manure, rice bran and soybean meal) with different weights (1, 3 and 5 gr) on larval development, the best time of harvesting at different constant temperatures (16-20, 22±1, 24±1, 26±1, 28±1 and 30±1°C) and the yield (larval live weight (gr) m-2 per week) based on the number of reared egg masses with the favorable diet. Results indicated that the highest weight of harvested larvae obtained when they fed on 5 gr of chicken manure (3.53±0.4, P < 0.01). The last larval instars were harvested at the shortest time (on 13th days), when reared at 24±1 or 26±1°C feeding on chicken manure (compared to other temperatures). Mean yield of 131.38± 13.99 gr m-2 per week obtained, when five egg masses were reared at 26±1°C on the chicken manure.

In most aquatic ecosystems mercury accumulates more in the sediment than in water column. However, due to limited eco-toxicological data, it is difficult to predict the toxicity of these sediments. The present study evaluated the effects of inorganic mercury in spiked sediment on the survival, growth, and emergence of the midge CHIRONOMUS RIPARIUS and compared the results to mercury concentrations reported in streams and rivers in Africa. At 3.84 mg Hg/kg dry sediment, mercury significantly reduced larval survival and midges emergence success in comparison to control sediment (P<0.05). The growth of the larva was significantly inhibited (P<0.05) at 2.42 mg Hg/ kg dry weight, while emergence of C .RIPARIUS midges was significantly delayed at 0.93 mg/kg dry wt. These results indicate that mercury inhibits C. RIPARIUS characteristics at lower concentrations than those which have been measured in sediments from watersheds impacted with mercury like those found around artisanal gold mining in Africa. It is therefore possible that CHIRONOMUS and probably other fauna living in these watersheds are at risk.

Breeding and cultivation of native chironomid (CHIRONOMUS albidus) midges of the Guilan Province were carried out to produce larvae in rearing system and to be also used for feeding fish larvae and fingerlings. In this study, 4 metal trays (65×65×10 cm) and 6 plastic basins with the capacity of 35 L were designed and built. Trays and basins were installed vertically and then equipped with aeration and water supply systems. In small part of the rearing site, a 2-liter fiberglass tanks was used for collection of egg clutches. After collection and introduction of egg clutches into the trays and plastic basins, the amount of harvested chironomid larvae were calculated during a consecutive rearing period. A total of 0.978 kg/m2 larvae of chironomid will be produced and harvested daily under rearing conditions. Results obtained from this study revealed that 382 g/m2 chironomid larvae were harvested on the 15th day of rearing as a percentage of the first reared group and then a total of 2 kg/m2 larvae were obtained periodically from all the population of a group on the 16th day of rearing.

Chironomid community in the southern coast of the Caspian Sea was investigated. Samples were collected with a Van veen grab in summer 1994 and spring 1995, at 16 sites of 10, 20, 50 and l00m depths located along the benthal zone in the southern shoreline. Chironomid larvae were taken from samples and preserved. The preserved material was examined microscopically.All the studied larvae belonging to the southern coast of the Caspian Sea were identified as CHIRONOMUS albidus.

This study was carried out in conversation area "Khojir", east of Tehran in October 1998. Specimens of CHIRONOMUS sp. and G. fasciatus were collected by a 0.04μ mesh size net and transferred to Shilamayesh Consulting Engineer Company lab and kept in refrigerator. Then, the number of casualty for both species in different cultures including cobblestone, sand, weed and rotten leaves have been counted and tested for feeding responses. In a 62 days period of the study, the maximum casualty numbers of G. fasciatus (26) was found in sand culture; whereas, for CHIRONOMUS sp. was in cobblestone by a number of 30. The minimum casualty amount of CHIRONOMUS sp. and Gammarus fasciatus were 9 and 18 in an algal culture, respectively. There was no significant difference before and after feeding for both CHIRONOMUS sp. and G. fasciatus. Also there was no significant difference between different cultures and the amount of casualty. This study aims to investigate the possibility of keeping CHIRONOMUS sp. and G. fasciatus in vitro in order to feed cultured fish.

Chironomids (Diptera) include the most abundant group of macroinvertebrates. They are usually collected from aquatic environments for quality evaluation. Tolerant aquatic organisms such as Chironomids are more abundant in polluted sites. This note makes the Chironomids as an excellent bioindicators. This group is not characterized in Anzali Wetland as well. So that, the aim of this study was to recover and characterize chironomid larvae in this wetland. Hence, Chironomid larvae were collected on the seasonal basis from 13 stations in the wetland. The main characteristics for their identification were eye spot, mentum, ventromental plate, antenna, and ventral tubules. The mitochondrial cytochrome oxidase I (COI) gene was applied to simplify the identification of CHIRONOMUS species by polymerase chain reaction (PCR) and sequencing method. The nucleotide sequence alignments were used for construction of the phylogenetic trees based on maximum likelihood method. Six genera were identified in three subfamilies, including: Chironominae (1 genus), Orthocladinae (1 genus), and Tanypodinae (4 genera). Based on ventral tubules, the dominant population of CHIRONOMUS larvae found in this study, lie in thummi and plumosus types. Five genera were reported for the first time from Anzali Wetland. The dominant genus was CHIRONOMUS. These groups of larvae were ultimately identified as CHIRONOMUS plumosus reporting for the first time from the wetland. It was also found that the Chironomids diversity is higher than those described in few studies before, however, further studies are still needed.

Objective: The orange-red spectrum of the skin of electric yellow (Labidochromis caeruleus) is one of the idealistic and necessary schemas sought by aquarists and commercial producers. In this study, the effect of live foods meal on the skin coloration of juvenile electric yellow was examined.Methods: 270 fish with an average living body weight was 0.42±0.11 g, and average total length was 3.3±0.35 cm. Their sex was not taken into consideration.. The fish were fed twice in the morning and afternoon by 3-5 percent of the biomass for 8 weeks. The six different treatments (three replicates/treatment) used in the experiment were used. Skin color was measured in below the dorsal fin of all fish. Measurements were recorded at the end of the feeding trial using a Konica Minolta Chroma Meter CR400.Results: At the end of the trial, the carotenoid supplemented diets significantly increased the values of redness (a*), yellowness (b*), and chroma (C*), and decreased the values of lightness (L*) and hue (Hoab) on the tail, body, and head areas (p<0.05). luminosity (L*) and hue (Hoab) were less in fishes fed the diets with live foods and astaxanthin than in fishes fed the control diet with no pigment sources (p<0.05). yellowness (b*), and Chroma (C*) were greater in fish fed the culex and were less in fish fed the control diet(p<0.05). Results show that live foods used in this trial can be used as an alternative natural carotenoid source in electric yellow diets.