International Journal of Aquatic Biology
Volume:3 Issue: 4, Aug 2015

Malathion is one of the most commonly used pesticides in agriculture. This study was aimed to investigate the acute toxicity of malathion as an aquatic pollutant on the behavior and hematological indices in Indian carp (Cirrhinus mrigala). A static experiment was conducted and 1, 24, 48, 72 and 96 hrs LC50 values of malathion for the test fish were estimated as 14.55 mg/L, 12.48 mg/L, 11.56 mg/L, 10.85 mg/L and 9.32 mg/L, respectively. During 96 hrs exposure to 9.32 mg/L of malathion, behavioral abnormalities such as hyperactivity, cough, convulsions, erratic swimming, loss of balance, rapid opercular movements, gill mucous secretion, surfacing and gulping of air were observed in the test fish. The hematological changes in exposed fish after 96 hrs exposure to malathion included a significant decrease in erythrocyte count, hemoglobin content, hematocrit, leukocyte count and a significant increase in neutrophils count as compared to the control fish. In conclusion, acute exposure to 9.32 mg/L of malathion provoked behavioral and hematological abnormalities in Indian carp which offers a valuable tool to monitor malathion induced toxicity in fish.

Wetland Zooplankton Index (WZI) was developed for the low country intermediate zone of Sri Lanka using 20 reservoirs located between latitudes 7°20'22.081"N - 7°48'33.558"N and longitudes 80°1'44.55"E - 80°9'51.509"E. WZI ranged from 1.56 in Anukkane reservoir which is located in a low flat terrain in the midst of agricultural lands to 3.69 in Tampana reservoir which is located in a hilly area with a watershed mainly covered with forests. WZI showed a significant negative correlation with the Nitrate-N content (r = -0.797) and cumulative content of Nitrate-N and total phosphorus (r = -0.795) indicating that it can be used as an indicator of the degree of eutrophication of inland reservoirs in the low country intermediate zone of Sri Lanka.

The systematics, morphology, distribution, biology, economic importance and conservation of the bull shark (Carcharhinus leucas) in Iran are described, the species is illustrated, and a bibliography on this fish in Iran is provided.

Investigation on the food and feeding habits of silver carp in Gobindsgar reservoir indicated that the diet of silver carp was dominated by Cyclotella spp. (diatom) followed by Chlorophyceae, Cyanophyceae, Crustacea, Dianophyceae and Rotifera. The size range of Cyclotella spp. varied between 5-25 µm indicating that silver carp is capable to collect the food particles smaller than distance between its gill rakers. Probably, excretion of mucus plays an important role in collecting such small particles. By applying Costello method, it was concluded that Cyclotella spp. is very important food item while the others are general food items in the diet of silver carp in this water body. Study of diet overlap index of different size groups revealed that the value of “D” varied between 0.461 (moderate) to 0.972 (high), indicating that the diet of small size groups was significantly different from those of large size groups. The present observations indicated that the diet overlap index between female and male silver carp was very high (0.915), clearly indicating that the diet of male and females specimens did not differ significantly. Analysis of gut contents of silver carp indicated that zooplankton comprised only 7.7% by number and 19.3% by volume in the fore–gut contents of this fish, hence, silver carp can be considered as microphytoplankton feeder.

Organization of various cells lining the olfactory mucosa of Puntius ticto (Hamilton, 1822) were described by light as well as scanning electron microscopy. The paired olfactory chambers located antero-dorsal to the eyes and communicated outside through anterior and posterior nasal openings. The oval shaped olfactory rosette lied at the bottom of chamber and composed of 18-20 lamellae arranged on either side of median raphe. Sensory and non-sensory regions were distributed separately on each lamella. The sensory epithelium consisted mainly of two distinct morphological forms: ciliated and microvillous receptor cells. The non-sensory epithelium contained ciliated non-sensory cells, stratified epithelial cells with concentric microridges and mucous cells. Basal cells were situated at the deeper part of the epithelium, adjacent to the central core. The functional significance of cellular components of the olfactory epithelium was discussed with the habit and habitat of fish.

Calanoid, cyclopoid, harpacticoid and poecilostomatoid copepods were investigated over the year at five stations in the Chabahar Bay, Oman Sea. This area is under the influence of the Indian Ocean seasonal monsoons. The samples were collected using vertical plankton tows with 100 µm mesh nets. Copepods were identified into 20 genera and 59 species. Calanoid formed about 15% to 62% and cyclopoid 26% to 39% of total copepod abundance. Harpacticoid constituted about 6% in South West (SW)-monsoon and flourished well in pre (SW)-monsoon, formed 46% of copepod abundance. Poecilostomatoid accounted for approximately 5% to 13% of the total copepods. The most dominant species were Temora turbinata, Paracalanus elegans, Oithona nana and Euterpina acutifrons. The results showed that the species composition and distribution of copepods differed between the monsoon seasons, due to changes in hydrographic conditions. Furthermore, high abundance of small-sized copepods observed in offshore stations.

This study reports the length-weight relationship (LWR), Fulton's condition factor (K), and sex ratio of the non-native catfish Hoplosternum littorale (Hancock, 1828) in Florida for the first time. Sampling was conducted from November 2013 to April 2014 in Tosohatchee Wildlife Management Area in Christmas, Florida. A total of 477 specimens were caught (6.4-13.5 cm TL). The allometric coefficient b of the LWR was greater than the isometric value (b=3.11), suggesting positive allometric growth. The average value for Fulton's condition factor (K) was 1.396, with no significant differences between juvenile and adult size classes. The results present certain disparities from data recorded from the fishe's native range, suggesting that this freshwater invasive may be flourishing in Florida. In addition, a new maximum total length of the species is reported.

This study provide a new and updated checklist of the freshwater fishes of the Dasht-e Kavir basin of Iran. The list is based on historical literature records and taxon occurrence data obtained as a result of extensive field expeditions, examination of ichthyological collections and literature review. The total confirmed freshwater fish species of the Dasht-e Kavir basin comprise 22 species in 17 genera, 6 families, 4 orders and one class. The most diverse order is the Cypriniformes with 18 species (81.82%) followed by Cyprinodontiformes (2 species, 9.09%), Salmoniformes and Gasterosteiformes each with 1 species (1 species, 4.55%). The most diverse family is the Cyprinidae with 18 species (72.73%), Nemacheilidae (2 species, 9.09%) followed by Salmonidae, Cyprinodontidae, Poeciliidae and Gasterosteidae each with only one species (4.55%). New species are supposed to be discovered, the taxonomic status of some species has been changed, some are being resurrected from synonymy, and some taxonomic problems remain and are commented on briefly. Four endemic species (18.18%) in 4 genera and 2 families; and 12 exotic species (54.55%) in 10 genera and 4 families are listed here.