Biofloc technology (BFT) is an approach in the rearing of fish and shrimp as a means to support intensive culture, maintain optimum water quality, recycle the nutrients and reduce feed costs. The technology is primarily based on the principle of recycling nitrogenous wastes into microbial biomass that can be assimilated by the cultured animals as feeds or facilitates in maintaining good water quality. The rearing of larvae and juveniles of ornamental fish is confronted with issues on low survival rate, poor water quality and high incidence of diseases. These problems can be mitigated through the use of biofloc technology. From a number of studies reviewed, BFT offers a viable approach in ensuring sustainable production of ornamental fish. The benefits of using this technology include enhancement of water quality by reducing the levels of nitrogenous wastes, efficient feed conversion resulting in better growth and reduction in production costs and better immune response that will enable the fish to have higher resistance against infectious diseases.

The silver therapon Leiopotherapon plumbeus is an important but dwindling freshwater food commodity in Philippine freshwater habitats. The influence of feeding regimes on growth performance and survival of first-feeding silver therapon larvae fed euryhaline rotifers (Brachionus rotundiformis and B. plicatilis) as starter food was examined. Larvae at 2 days post-hatch (DPH) (1.93 ± 0.07 mm; 200 larvae/basin) were initially reared on rotifers for 12 days followed by Artemia nauplii from 14 to 35 DPH as follows: (A) B. rotundiformis from 2-13 DPH; (B) B. rotundiformis from 2-7 DPH and Moina micrura from 8-13 DPH; and (C) B. plicatilis from 2-13 DPH. After 35 days of rearing, mean survival rates were significantly higher in larvae fed B. rotundiformis (69.2%) than those co-fed B. rotundiformis and M. micrura (34.6%) or B. plicatilis alone (26.3%). Higher ingestion rates were observed for B. rotundiformis-fed larvae (1.6 ± 0.5 to 4.4 ± 0.5 ind larvae^-1) than larvae fed B. plicatilis (0.0 to 3.2 ± 0.8 ind larvae^-1) during the critical initial feeding stage. However, larvae fed B. plicatilis (20.75 ± 0.48 mm) were significantly longer than those fed B. rotundiformis alone (15.62 ± 0.40 mm) or co-fed B. rotundiformis and M. micrura (18.57 ± 0.58 mm). The fastest growth was observed in larvae fed B. plicatilis, with length increment (LI) and specific growth rate (SGR) of 18.8 mm and 6.8% day^-1, respectively. Eye diameter, head length, snout length and pre-anal length increased but were not affected when larvae were fed two rotifer species. These results demonstrate that feeding euryhaline rotifer B. rotundiformis from 2 to 13 DPH followed by Artemia is a suitable feeding regime for better survival of silver therapon larvae under laboratory rearing conditions.

Threshold infection level is the pathogen load of the test animals measured before the appearance of clinical signs and mortality. This study aims to establish the threshold infection levels of WSSV in different weight ranges of Penaeus vannamei using qPCR. Artificial infection experiments were conducted using four weight ranges (3–5 g, 7–8 g, 15–18 g, and 22–25 g). The LD₅₀ of the different weight ranges of shrimps were achieved at viral dilution of 10^-6 and 10^-5 after 216–240 hpi, and the viral loads of these inoculums have a range of 10⁵–10⁶ WSSV DNA copies/g. The viral loads of the samples in the timecourse infection experiments when the mortalities started was determined at 10⁹ WSSV DNA copies/g, while for the survivors was at 10⁶ WSSV DNA copies/g. The threshold infection level of WSSV in shrimp was determined at 10⁷ to 10⁸ WSSV DNA copies/g. It was also found out that the threshold infection level was not weight dependent.

Infectious diseases caused by viruses and bacteria are a major threat to sustainable shrimp farming globally. Since early 80’s viral diseases such as White Spot Disease, Taura Syndrome disease have caused enormous losses to shrimp aquaculture both in eastern and western hemisphere. As the shrimp industry tried to recover from the onslaught of these diseases, a bacterial, Acute Hepatopancreatic Necrosis Disease (AHPND), also known as Early Mortality Syndrome, and a fungal disease Hepatopancreatic Microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) are now posing new threat to shrimp aquaculture. Acute Hepatopancreatic Necrosis Disease is caused by Vibrio spp. expressing plasmidborne binary toxins, PirA and PirB that is similar to entomopathogenic bacterium, Photorhabdus encoded toxin. In 2009, AHPND emerged in China and since then spread to many countries in East Asia and in the Americas. Another disease that has caused alarm in recent year is Hepatopancreatic Microsporidiosis (HPM) caused by Enterocytozoon penaei (EHP), a microsporidium. While AHPND causes acute infection and large-scale mortalities, EHP causes chronic infection and results growth retardation and size variation in population reducing marketability of the infected shrimp. Both diseases affect hepatopancreas, an organ involved in metabolism and humoral immunity in shrimp. The binary toxin, PirA/ PirB are the primary virulence factor for AHPND, but specific virulence factor(s) for EHP is not known. It is, however, known that EHP does not have mitochondria and appears to transport ATP from the cytoplasm of infected cells as it contains ATP transporter genes in its genome. EHP has been shown to be a risk factor for AHPND. Due to lack of therapeutics, preventative measures remain as a corner stone for managing these diseases and efforts are underway to develop genetically improved lines of shrimp having resistance to AHPND and EHP.

Aquaculture is an important industry in Thailand which has been established more than two decades ago. The cultured species are divided into two main groups; shrimp and finfish farming. The major cultured shrimp species are Penaeus vannamei (Pacific white shrimp), P. monodon (black tiger shrimp) and Macrobrachium rosenbergii (giant freshwater prawn), whereas the finfish are Oreochromis sp., Lates calcarifer and Epinephelus sp. Also, ornamental fish such as Cyprinus carpio (Koi carp), Carassius spp. (goldfish), and Betta splendens (fighting fish or betta). Disease outbreaks are the key factor that affect Thailand’s aquaculture production and resulting in economic losses. The infectious diseases in aquaculture are mainly caused by viral and bacterial pathogens. In 2018, the reported shrimp pathogens are white spot syndrome virus (WSSV), yellow head virus (YHV) genotype 1, Taura syndrome virus (TSV), infectious hypodermal and haematopoietic necrosis virus (IHHNV), Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VPAHPND), and microsporidian Enterocytozoon hepatopenaei (EHP). On the other hand, the reported pathogens in finfish are Betanodavirus causing viral nervous necrosis (VNN), Tilapia lake virus (TiLV) and Streptococcus sp. etc. In Thailand, the Department of Fisheries (DOF) is the competent authority for various aspects of aquatic animals including aquatic animal health. Strategies to prevent and control diseases in aquatic animals include issuance of legislations/regulations, implementation of biosecurity measures, disease surveillance programs, capacity building, cooperation with international and national organizations. Moreover, DOF has developed contingency plan in dealing with aquatic animal disease emergencies through the provincial fisheries officer. The provincial fisheries officer acts as director of emergency aquatic animal disease control center in each province, while Aquatic Animal Health Research and Development Division (AAHRDD) and Songkhla Aquatic Animal Health Research and Development Center (SAAHRC) serve as disease diagnosis and laboratory testing centers. Because of the above actions, we are capable of preventing and controlling disease outbreaks in the country. But during the occurrence of some diseases, we have no treatment to support and completely solve the problem. Example are viral diseases, unlike bacterial diseases which can be treated by using chemical or drug. Furthermore, there are a few researches that could be applied in farm level. Especially shrimp which has no adaptive immunity, so it is difficult to develop vaccine compare to fish. Therefore, DOF mostly recommended farmers to follow the good management practices on aquatic animal health for promoting sustainable aquaculture.

The national aquatic animal disease surveillance and reporting system is implemented by the Bureau of Fisheries and Aquatic Resources in coordination with other recognized laboratories. It covers the OIE/NACA listed diseases particularly those that cause major problems in aquaculture. The fisheries laboratories continuously enhance their capabilities to support the surveillance activities, controls on transboundary movement of aquatic animals, and provide services to the fish farmers. Programs are implemented to strengthen the aquatic animal health services in the country. Promotion of Good Aquaculture Practice and implementation of biosecurity measures are being done to prevent disease occurrences. Collaboration with other institutions on aquatic animal health programs are also established. The paper provides the information on the country’s status on aquatic animal health management.

The fisheries sector of Malaysia plays a significant role in economic development. It provides employment, foreign exchange and protein supply for the country. In 2017, aquaculture production in Malaysia was 427,022 tonnes, a 4.8 % increase compared to 2016. The increase was driven by population growth, rising demand for seafood and a levelling of production from capture fisheries. However, the rapid growth of aquaculture has been source of anthropogenic change on a massive scale. Aquatic animals cultured in high density are exposed to environment stress leading to diseases. Among major diseases occur in Malaysia are TILV and Streptococcosis in Tilapia, Vibriosis in grouper, and APHND and EHP in shrimp. Losses due to these diseases were reported as USD 0.1 billion for APHND in 2011, MYR 1 million due to Streptococcosis in 2002 and USD 7.4 million in Vibriosis outbreak in 1990. Currently the use of chemicals to overcome these diseases by farmers has led to increase concerns on food safety of food fish. Thus, Malaysia has implemented strict biosecurity measures in fisheries practices to secure not only fish health but also food safety for the consumers. This paper aimed to discuss the status of fish diseases and national diseases response and surveillance in Malaysia.

Fish disease is one of the main obstacles in the success of aquaculture production because of the loss caused by it. The outbreak of diseases has resulted to a substantial economic loss which was reported to have reached almost USD 400 million. To minimize the impact of losses caused by fish diseases, the Indonesian government through the Directorate General of Aquaculture, Ministry of Marine Affairs and Fisheries has a fish disease monitoring and surveillance program. The program aims to monitor the occurrence of fish diseases in Indonesia, especially in the fish and shrimp farming centers and to educate on how to control them. In 2018, the monitoring and surveillance program have 34 provinces with 100 districts/cities location targets targeting fish and shrimp diseases. Based on the results of the monitoring and surveillance activities in 2018, the fish and shrimp are affected by the following diseases: White Spot Syndrome Virus (WSSV), Infectious Hypodermal and Haemotopoietic Necrosis Virus (IHHNV), Infectious Myonecrosis Virus (IMNV), Iridovirus, Aeromonas hydrophila, Streptococcus iniae, Streptococcus agalactiae, Edwardsiella ictaluri and Ichthyophthiriasis. The program to control fish diseases in order to minimize the losses has also been carried out by the government including trainings on the application of biosecurity, the use of vaccines, probiotics, immunostimulants and herbal medicines.