Composition and abundance of larval fishes in Campeche Bay were studied during two seasons, winter, 2013 (24 stations) and summer, 2014 (31 stations). Sampling was carried out with open-close nets, mouth 75 cm and 505 µm mesh. The data of salinity and temperature allowed distinguishing three oceanic sub-regions: North, East, and West. There were 236 taxa, belonging to 74 families, 168 species, 154 taxa occurred in winter and 171 in summer; the composition in both cruises was similar with around 70 % of oceanic and 30 % of neritic larvae. The larval density was almost three times larger in summer than winter. The Campeche Bay hydrodynamics fits well with the results; the West sub-region is located where a cyclonic gyre takes place, the North and East sub regions are located in the area of influence of warm currents over the Yucatan shelf. The hydrodynamics also allows understanding the differences in the proportion of neritic larvae among the three oceanic sub-regions, the West and East with the lower and higher number of neritic larvae, respectively. The large difference among regions is related to some neritic taxa occurring exclusively in some of them. Of the total taxa, 55 neritic occurred only once and it means that more than a half of neritic taxa were represented by one organism, 31 from 85 neritic taxa occurred in the layers of 600 to 1000 m depth. Of the neritic larvae, only Syacium papillosum and Apogon sp. appear among the 20 more abundant.

This study was conducted to determine the effects of photoperiod on egg hatchability, growth and survivability of hybrid catfish (Heterobranchus bidorsalis X Clarias gariepinus) larvae, using hormone-induced spawning method. Eggs were stripped from two sexually matured and healthy female Clarias gariepinus of average weight of 1kg/each and fertilized with milt from two sexually matured male Heterobranchus bidorsalis of average weight of 2kg/each. An average of five hundred (500) eggs were introduced into each ten aquaria tanks of size 70cm x 45cm x 40cm/tank, using a pre- determined spoonful estimation at five photoperiod regimes: (T1) 24L:00D (Light:Darkness); (T2) 18L:6D; (T3) 12L:12D; (T4) 6L:18D and (T5) 00L:24D in two replicates. Aquaria tanks were arranged in a flow- through system at a flow rate of 1.5L/min with aerators to maintain good water condition. Provision of light during the night for illumination of the aquaria tanks was kept constant at 1200 1x, using solar panel (Mono)/inverter (Microtex) light energy. Growth and survivability of the fish larvae were monitored for six weeks. They were fed with laboratory-cultured live feed (Daphnia) to achieve maximum feed utilization. Percentage hatchability of eggs and best growth performance of fish larvae were significantly (p<0.05) highest (92.5%, 91.2 ± 0.21mg) respectively in T5 (00L:24D), while percentage survivability of hatchlings was significantly (p<0.05) highest (94.4%) in T3 (12L:12D). It was observed in this study that the highest hatchability of eggs and optimum growth performance of hatchlings were under complete darkness, with reduced survivability of fish, as a result of observed cannibalism. The fish were photophobic. To achieve a balance result in terms of hatchability of eggs, growth and survivability of fish fry, it is suggested that incubation and hatching of eggs should be done under complete darkness, while rearing of fry should be under equal light and darkness exposure.

About 60-70% of world’s biological resourcesis contributed by India, of which fish represents 80% of the global fishes. Uttar Pradesh blessed with vivid aquatic bioresources in innumerable forms contributes about 14.68% of Indian fish biodiversity with substantial scope of inland fisheries development and aquaculture. Ganga, the mighty river of this state reportsabout 265 freshwater species from its river system [1]. Besides, other rivers viz. Ramganga, Gomti, Ghaghara, Yamuna, Gandak, Kosi and Damodaract as reservoir of different f ish stocks. In past, no study highlights the assessment of the fish biodiversity of this state in holistic way except by Khan (2000) who justreported a compilation of 129 fishes under 27 families [2]. To substantiate and revise the assessment, the fish diversity of this state was assessed by investigating these rivers, analyzing and documenting the information on different fisheries measurements including biology, distribution and conservation status. About 10,000 individuals were collected and the analysis of individuals revealed 126 fish species under 28 families and 74 genera nearly mitigating the earlier reports. The highest species diversity was recorded in the river Ganga (90) followed by Gerua (87) and then Gomati (68). 37 species were found common in Gomati, Ghaghara, Ganges, Son, Tons and Yamuna. Out of 90 species, 6 species were recorded from the river Ganga. In addition, the new distribution of a threatened torrent catfish Amblyceps mango is was recorded from the rivers Gomati, Ganga and Ramganga. The economical assessment unravels nearly 33% as ornamental, 87% as food and 10% as sport fishes.

Among anthropogenic threats to marine mammals, bycatch is one of the major and increasing concerns. This report describes three species of small cetaceans, including a short-beaked common dolphin (Delphinus delphis), a bottlenose dolphin (Tursiops truncatus), and two dwarf sperm whales (Kogia sima), which were found stranded with pectoral fins, dorsal fins and caudal fin removed. The dolphins were found at the beaches of San José de Las Nuñez and San Pablo, respectively (Santa Elena Peninsula Province on 14 August 2017), while the dwarf sperm whales were found in Puerto Lopéz and Crucita (Manabí Province) in July 2014 and August 2015, respectively. Possible explanation for the dolphins and dwarf sperm whales missing fins support the event as a possible case of fishery interaction or bycatch with systematic removal of their fins. Although remnants of artisanal gillnets were not found near the two dolphin species, one of the dwarf sperm whales showed marks of artisanal gillnets on the body as evidence of bycatch. Trade of dolphin carcasses and their parts for bait by fishers cannot be ruled out as there is some evidence of this practice in the past. Both dolphins species are vulnerable species at the national level and commonly involved in incidental captures with gillnets of artisanal fisheries in Coastal Ecuador. Cetacean bycatch is a grave conservation problem affecting several cetacean species in Ecuador’s waters. Fisheries and environmental authorities must be vigilant and enforce actions to proactively mitigate possible anthropogenic impacts and promote environmental education activities in fishing communities to conserve vulnerable dolphin species in Ecuador’s waters. Further, to comply with new rules and regulations of the US Marine Mammal Protection Act (MMPA) intended to reduce the bycatch of marine mammals in foreign commercial fishing operations that export fish and fish products to the United States, a regulatory program is urgently needed to mitigate and reduce fisheries interactions with marine mammals in Ecuador.

Toxic metals have contaminated the aquatic ecosystems to a large scale, and they eventually enter human systems by contaminated air, food, water and soil. Recently, arsenic toxicity has become an alarming concern around the globe. Major areas of North-Eastern states of India have been demarcated with an arsenic content of 50-1000 µg/l in drinking water sources and aquatic ecosystems. Arsenic range in Barak Valley is many folds higher than the permissible limit of WHO and BIS as 10µg/l and 50µg/l respectively, which is present in the form of Sodium Arsenite in water. Fishes are the major dwellers of aquatic ecosystem and serves as good bio-indicators for determination of health status of an aquatic ecosystem. They also form the staple diet of North Eastern people. Labeo rohita is one of the most commonly available and consumed in large scale. The present study was carried out in Labeo rohita in vivo. Labeo rohita (n=10) of similar size and weight were exposed to sodium aresnite at concentrations 100 µg/l and 250 µg/l along with controlled set up for 10 days. The morphological, behavioral, hematological and histopathological changes were evaluated. Fishes exposed to Sodium arsenite showed irregular ocular movement, fin movement, swimming pattern and loss in scales with higher prominence in 250 µg/l of arsenic group than those at 100 µg/l. The hematological indices revealed decrease in RBC count and increase in WBC count in both sodium arsenite exposed groups. The histopathological study of liver revealed parenchymal disorganization and atypical residual body in both sodium arsenite treated groups. Results obtained showed major damages to fishes due to contamination with sodium arsenite. These fishes, when consumed by humans, leads to increase in several thousand folds of sodium arsenite by means of biomagnification. High exposure of arsenic in human through fishes leads to several disorders. The possible way of eradicating sodium arsenite entry into humans is banning fishing activities in highly contaminated aquatic ecosystems. Community education and local participation are also essential to get a fruitful outcome.