Chitin was first discovered by its name from the Greek word “chiton”, which means “mail coat”. It is indeed a polysaccharide made up of naturally occurring acetyl-D-glucosamine monomers. Hatchett was the first researcher who extracted chitin from the shells of mollusks (crabs and lobsters), prawns, and crayfish in 1799. Later in 1811, Henri Braconnot discovered chitin in the cell walls of mushrooms and called it “fungine”. Chitin and chitosan are abundant in the biosphere as essential components of many organisms’ exoskeletons and as by-products of the global seafood industry. The biopolymer must be deacetylated before chitosan can be produced. It can also be extracted using microbes in a biological extraction procedure. The development of products that take advantage of the bioactivities of the existing primary commercial source of chitin (crustacean) has lagged expectations. Also, the disadvantages of the present commercial source such as seasonality and competition for other uses among others has been one of the driving forces towards seeking alternative sources of chitin and chitosan in nature. This review highlights some of the efforts made by environmental scholars to locate possible commercial sources of chitin and chitosan in nature over time.

Aquaculture has been celebrated globally and believed to usher in a viable alternative to capture fisheries. It is most welcomed especially now that the world population explosion has pushed the demand on fisheries products to worrisome limits. Shrimp farming is an area of aquaculture that has witnessed significant growth in recent years, contributing substantially to the global aquaculture production. However, intensification of shrimp aquaculture has come with unintended consequences such as wastewater management and other problems emanating from environmental impact of the wastewater. This study identified excess feed and fertilizer application, metabolite wastes, shrimp mortalities, oil spillage from farm machines, drug and chemical abuse as some of the activities contributing to wastewater generation in shrimp aquaculture farming. The impact of shrimp effluent water discharged has been observed to be socio-economic with both positive and negative dimensions. In attempt to overcome the overwhelming problems associated with shrimp effluent water and bring reassurances to its sustainability, a good number of new technological approaches have been identified including caviation, high-rate algal pond system, use of nanomaterials, biofloc technology, nanoadsorbent and polymeric nanoadsorbents. Although all have been proven to be useful, none could boast of a complete and integrated approach that considers all the technological, legal, social, environmental, public health and institutional concerns.

Dietary lipid manipulation in the feed of commercially cultured finfish is used not only to improve production and culture but also to enhance their reproductive performances. The inclusion of lipid in broodstock diet positively affects growth, immunological responses, gonadogenesis, and larval survival. In this review, existing literature on the importance of freshwater finfish species to aquaculture and the inclusion of dietary lipid compounds in freshwater fish feed to accelerate the reproduction rate is being summarized and discussed. Although lipid compounds have been confirmed to improve reproductive performance, only a few members of the most economically important species have reaped benefits from quantitative and qualitative lipid studies. There is a knowledge gap on the effective inclusion and utilization of dietary lipids on gonad maturation, fecundity, fertilization, egg morphology, hatching rate, and consequently, larval quality contributing to the survival and good performance of freshwater fish culture. This review provides a baseline for potential future research for optimizing dietary lipid inclusion in freshwater broodstock diets.

The major sources of waste from aquaculture operations emanates from fish or shellfish processing and wastewater generation. A simple technique called coagulation/flocculation utilizes biowaste from aquaculture to produce chitosan coagulant for wastewater treatment. A chemical method was applied in the present study for chitin and chitosan extraction from carapace of Macrobrachium rosenbergii and subsequent application for removal of turbidity and salinity from shrimp aquaculture wastewater. Box-Behnken in RSM was used to determine the optimum operating conditions of chitosan dosage, pH, and settling time, after which quadratic models were developed and validated. Results show that 80 g of raw powder carapace yielded chitin and chitosan of 23.79% and 20.21%, respectively. The low moisture (0.38%) and ash (12.58%) content were an indication of good quality chitosan, while other properties such as water-binding capacity (WBC), fat-binding capacity (FBC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) confirmed the structure and the α-group, as well as the rough morphology of chitosan. In addition, the high solubility (71.23%) and DDA (85.20%) suggested good coagulant potentials. It was recorded in this study that 87.67% turbidity was successfully removed at 20 mg/L of chitosan dosage and 6.25 pH after 30 min settling time, while 21.43% salinity was removed at 5 mg/L of chitosan dosage, 7.5 pH, and 30 min settling time. Therefore, the process conditions adopted in this study yielded chitosan of good quality, suitable as biopolymer coagulant for aquaculture wastewater treatment.