In this issue:

  • Neolissochilus hexagonolepis (chocolate mahseer): A flagship species for diversification of hill aquaculture in Northeast India
  • Aquarium fish culture in open village ponds in South 24 Parganas, West Bengal
  • Women nurtured transformative aquaculture in rural Bengal
  • Breeding and seed production technology of striped spiny eel Macrognathus pancalus to benefit fish farmers
  • Grow-out culture of the loach Lepidocephalichthys thermalis in modified tanks
  • NACA Newsletter

This article investigates the ecological, economic, and cultural importance of Neolissochilus hexagonolepis, commonly known as chocolate mahseer and its potential for hill aquaculture in Northeast India. The taxonomy, distribution, and distinct features are described. Chocolate mahseer populations are in decline due to habitat degradation, overfishing and environmental changes, and it is designated as "near threatened" by the IUCN. Breeding patterns, growth parameters, and culture techniques are explored in depth as a candidate species for aquaculture development. Conservation initiatives and the need to balance economic utilisation with species conservation in chocolate mahseer farming are discussed.

The article highlights the successful commercial-scale breeding, propagation, rearing, and sale of aquarium fish species in the Howrah and South 24 Parganas districts of West Bengal, India. It focuses on the innovative practices of two experienced aquarium fish farmers, Sri Bikash Sau and Sri Swapan Parua, who have introduced a novel approach to aquarium fish culture in open earthen and common village ponds. The success stories of Sri Bikash Sau and Sri Swapan Parua serve as inspirations for small and medium-scale farmers and aqua-entrepreneurs. Their innovative approach to open pond production for aquarium fishes demonstrates the increasing potential and expansion of the aquarium fish business in the region.

Aquaculture has traditionally been a male-dominated activity. Changes in rural dynamics, with men migrating to cities for better opportunities, have led women to take up aquaculture in Bengal. Collaboration with Krishi Vigyan Kendras and local R&D institutions have provided them with training in ecological aquaculture, focusing on resource utilisation. Women engage in agro-ecological farming, utilising local inputs and traditional knowledge. The cooperative approach has enabled women to systematise production processes at a low cost, overcoming challenges and reviving local production. By forming self-help groups women have access to unconventional water resources and utilise mobile communication tools to strengthen the fish production system. The article discusses the broader role of women in diverse domains of aquaculture, including fish culture, hatchery management, nutrition, and fish processing technology, showcasing their resilience, capability, and contributions to the success of aquaculture.

The striped spiny eel, Macrognathus pancalus, is economically significant but faces population decline due to anthropogenic factors. This study presents a comprehensive approach to breeding and seed production techniques for M. pancalus, conducted at the Regional Research Centre, ICAR-Central Institute of Freshwater Aquaculture, Rahara, India. The study describes broodstock management simulation of natural habitat to stimulate natural breeding. Techniques for hatching and larval rearing, management of early spawn, and precautions to prevent cannibalism are presented. Survival of 88% after one month was achieved. The breeding and seed production techniques provided are suitable for farmers to adapt, and will contribute to the conservation and utilisation of M. pancalus in sustainable aquaculture practices. The findings also highlight the economic potential of this species to provide a nutritious option for consumers at affordable prices.

This study explores the cultivation of the Indian spiny loach, Lepidocephalichthys thermalis, in indigenously designed poly-lined iron frame tanks as a sustainable solution. The article details the fabrication methods for these tanks, highlighting the use of rust-resistant iron and low-density polyethylene sheets.The study proposes a supplementary feed mixture and provides insights into water quality management to ensure optimal conditions. The study demonstrates the potential for achieving a net production level of 1 kg from 400 liters, offering economic viability for farmers. The modified tank-based rearing system is shown to be beneficial in hilly regions with limited land and water resources.

Quality biological sampling is a fundamental requirement for all kinds of work on diagnosing diseases and screening for pathogens. Fish sampling requires specific techniques and skills to collect good biological samples for accurate disease diagnosis. This package of practices developed by WorldFish and partners provides advice on fish sampling protocols for routine disease diagnostics and outbreak investigations in tilapia, carp and catfish production systems. These sampling protocols provide guidance and training to project team members, researchers, resident veterinarians, extension officers and farmers tasked with collecting quality biological samples for laboratory diagnosis whenever disease outbreaks occur on farms or hatcheries. A free online introductory course on fish sampling for disease diagnostics is also available via Learn.ink.

Infectious diseases represent one of the major challenges and limitation to sustainable aquaculture. They can have major impacts on animal welfare, livelihood of farmers and threaten the health of captive stocks and wild populations. Pathogens can spread through movement of live fish, fish products, water and shared equipment. Routine screenings of pathogens in aquatic animal production systems are important to minimize the risk of their introduction, transmission and spread. On suspicion of a disease during abnormal mortalities, investigation with collection of biological samples from moribund animals must take place rapidly for disease diagnostics. Quality biological sampling is a fundamental requirement for all kinds of disease diagnostic and pathogen screening work. WorldFish and partners developed this rapid guide on sampling materials required for fish disease diagnostics. It lists all the personal protective equipment, the data collection/recording/cleaning supplies and sampling materials: consumables, reagents, media and tools needed to conduct one of the six quick fish sampling guides for disease diagnostics: 1. Wet-mount sampling guide (for ectoparasites & fungi) 2. Fish & water Microbiome sampling guide 3. Blood sampling guide 4. Bacteriology sampling guide 5. Molecular and virology sampling guide 6. Histology sampling guide.

A free online course on foundations in fish disease sampling is also available via Learn.ink.

Parasitic and fungal infestations represent one of the major challenges to sustainable aquaculture. As part of routine health checks or during abnormal mortality events, screening for ectoparasites and fungi in tilapia, carp and catfish production systems is important to minimize the risk of their introduction, transmission and spread. WorldFish and partners developed this quick guide for ectoparasites and fungi assessment under a light compound microscope. Standard wet-mount specimens consist of gill biopsy (gill clip), fin biopsy (fin clip) and skin scraping (mucus smears). Additional smears may be included in the presence of external lesions/ulcers (eye, skin, mouth). A free online training course on wet mount sampling is also available via Learn.ink.

Interactions between microbes associated with the host, other organisms present in the system and the environment itself are increasingly recognised to contribute to aquatic animal diseases. Those microbiome assemblages and their functions are extremely diverse and poorly understood. They vary over time in water and between host tissues and organs.

High-throughput sequencing technologies (multi-omics) and bioinformatics analysis of complex microbiomes can provide biological insights offering new opportunities for early detection of pathogens and disease mitigation strategies. Similarly, such approaches are being applied to study the effect of locally available ingredients for use in fish feeds and their impact on fist gut microbiome and the health of the pond environment—optimising the growing conditions on-farm.

WorldFish and partners developed this quick guide for microbiome sampling from fish skin/gills mucus swabs, internal organs (e.g. gut) and water samples from ponds, hatcheries tanks, river, and canals.

A free online training course on microbiome sampling is also available on Learn.ink.