The sandfish Holothuria scabra is a sea cucumber with a very high economic value. Sandfish cultivated in brackish water ponds will face a high salinity problem in the dry season. This study aimed to analyse the effect of high salinity on sandfish mortality. The study was done in a controlled tank in which the sea water was allowed to evaporate naturally, without the addition fresh water, so that the salinity increased continually. High salinity can cause injury and death to sandfish; before death, there was an evisceration. The death salinity of sandfish was 47 ppt. Sandfish have a greater range of tolerance to salinity than other sea cucumber species.

The sandfish Holothuria scabra is a benthic animal of high ecological and economic value. The high economic value of sandfish has led to declining populations due to overfishing. Initiatives to improve sandfish production have included restocking, sea-ranching and aquaculture (captive breeding and grow-out). These initiatives require a supply of animals (seed and/or broodstock) that often originate far from the location where they are needed. This calls for a good transportation system so that the sandfish arrive in good condition. This study aimed to assess the evisceration rate of sandfish transported using open and closed transportation modes. During the study, different modes of packing, density, transportation time, and holding time were evaluated. This study indicated that delivery using open systems gave poor results; besides being less practical, post-transport evisceration was very high. The ratio of oxygen and water and the packing density did not appear to affect the sandfish evisceration rate. Evisceration seemed to be triggered by the presence of dead and decaying sandfish in the bag. Sandfish that survived transportation generally recovered swiftly after being placed in a pre-prepared holding tank. The transported sandfish were used for multitrophic aquaculture and the post-transport survival ratio was very high.

Sandfish culture had been implemented for more than 20 years but has frequently failed to yield the expected results due to low survival rates. A decrease in salinity during the rainy season was suspected as a cause of sandfish mortality. This study aimed to assess the influence of salinity on sandfish survival rates. Treatments included sudden shock and gradual acclimation trial methods. Even though the results of this study indicate a mean survival rate of 50% at 14.6 ppt, the survival rate fell drastically as water salinity was reduced below the salinity of saltwater bony fish body fluids (around 18 ppt). Sandfish cannot live in water with salinity lower than the osmotic body fluid of freshwater bony fish (around 14 ppt). Therefore, for the cultivation of sandfish in coastal ponds, salinity should not be allowed to fall below a minimum of 18 ppt.

The Nile Tilapia Oreochromis niloticus is considering as a pest in shrimp farming ponds, as it is a shrimp competitor and predator of benthic organisms. This study aims to determine the effective and efficient saponins doses to eradicate tilapia without causing shrimp mortality. The study used two different saponins doses (200 kg/ha and 100 kg/ha) with seven different levels of salinity (5, 10, 15, 20, 25, 30, 35 ppt). The saponins doses used in this study had no effect on shrimp mortality, but had a significant effect on mortality of nile tilapia. The mortality of nile tilapia was 100% for all treatments. The death time of nile tilapia decreased significantly with increasing salinity. Longest nile tilapia death time was found at 10 ppt water salinity; this salinity is close to that of body fluids (14 ppt). The greater the difference between the ion content of body fluids and water ions in the test media, the faster the time of death. The effects of bleeding on the operculum, pectoral and caudal fins are more severe at high salinity. It is advisable not to increase the saponins doses, use the same saponins doses at any salinity, because predatory and competitive fish will die at any salinity.

Sandfish Holothuria scabra is a species of high economic value that causes sandfish to be the most captured sea cucumber species, and is an important source of income for fishermen in coastal villages. Sandfish capture causes already over fishing. If the wild population of sandfish is not managed properly, over fishing could cause sandfish extinction. This reason, an alternative efforts are needed to increase sandfish production, such as cultivation and restocking. Sandfish was a species that can live in the estuary region, so that it has the potential to be maintained in brackish water ponds. One of the problems of Sandfish cultivation in the brackish water ponds was the predators attack. This study aims to analyze the predator attack on sandfish. The study was carried out on a microcosm scale by using the tanks. The organism used was Sandfish H. scabra, Nile Tilapia Oreochromis niloticus, and seaweed Gracilaria sp. Mangrove Snail attack can cause death if the sandfish has already eviscerated. The healing process takes one to several weeks, depending on the size of the wound. Nile Tilapia attacks were generally not deadly. Death only occurs if the wound is too deep and causes internal organs to come out, but this was very rare. During the study, only one case occurred in which the sandfish died due to the attack of Nile Tilapia. The sandfish that not injured in the ventral side, and does not suffer from evisceration, the mortality was zero. Sandfish wounds heal within one to three weeks, depending on the surface area of the tegument eaten by Nile Tilapia. Healed wounds appear darker in color.