Koi Herpesvirus (KHV) or Cyprinid herpesvirus-3 (CyHV-3) is considered among the most damaging viral diseases of common and koi carp aquaculture across the world. Koi herpes virus causes high mortalities, economic losses, and trade restrictions in aquaculture industry. One of the major problems related to KHV is its capability to cause latent infection in surviving fishes. In latent infection, the virus exists in hiding within the host organisms without showing any clinical signs; mainly within leukocytes and nervous tissues. Latently infected fishes serve as silent carrier of the virus that can be reactivated under certain stress conditions such as temperature change, transportation, crowding, and poor water conditions. Reactivation causes shedding of virus from latently infected fish and further spread of virus among clinically healthy fish populations. Research has shown that KHV DNA can be detected in blood leukocytes and many other organs even in healthy carp. Temperature changes have been reported as one of the most important factors that induce viral shedding from latently infected fishes. The detection of latent infection is very difficult due to presence of extremely low numbers of viral DNA during latency stage. PCR and Realtime PCR have been used successfully to detect latent KHV infection. It is necessary to have good surveillance, biosecurity measures, stress reduction, and periodic screening in order to avoid silent transmission of the virus. It is vital to understand the process of latent infection and reactivation for sustainable carp farming.

Aquaponics, the integrated production of fish and plants in a recirculating system, has been promoted as a sustainable agriculture solution capable of reducing water use by 90-95% while producing protein and produce simultaneously without synthetic fertilizers. Despite decades of enthusiasm, commercial aquaponics remains economically marginal, with most operations failing to achieve profitability. This article synthesizes recent life cycle assessment data and systems engineering principles to examine why aquaponics struggles to scale. Key constraints include high energy demands (particularly in northern climates), dependence on industrially produced fish feed that undermines "closed-loop" claims, nutrient imbalances requiring synthetic supplementation, and capital-intensive infrastructure that cannot compete with conventional agriculture on cost. Decoupled system designs, renewable energy integration, and strategic market positioning offer the most viable pathways forward, though aquaponics will likely remain a niche rather than transformative agricultural technology.

The rapid growth of the global population has significantly intensified pressure on food production systems, leading to an excessive reliance on chemical fertilizers. India has now emerged as the second-largest consumer of fertilizers globally, reflecting the intensification of nutrient use to sustain crop yields (Anonymous 2025). While excessive reliance on chemical fertilizers initially boosted yields, it has resulted in severe soil degradation, nutrient imbalances, and environmental contamination. These challenges highlight the urgent need for precision nutrient management (PNM), which utilizes advanced technologies to manage spatial and temporal variability in soil nutrient supply to increase productivity and efficiency in an environmentally responsible manner. PNM is strictly guided by the 4R principles: Right Source, Right Rate, Right Time and Right Place. Various diagnostic tools and decision-support systems (DSS) have been developed to bridge the gap between high-yielding crop requirements and indigenous soil supply. Handheld sensors like the soil plant analysis development (SPAD) meter and green-seeker allow for real-time monitoring of plant vigour and chlorophyll content. Furthermore, the Leaf Color Chart (LCC) provides a cost-effective method for need-based nitrogen application. Analytical approaches such as soil test crop response (STCR) and the omission plot technique establish quantitative basis for maximizing profit and yield. Digital tools like nutrient expert and rice crop manager provide locationspecific recommendations that have been shown to increase yields across various agro-ecological zones.