Growth, Survival, and Behavior of Early Juvenile Sandfish Holothuria scabra (Jaeger, 1883) in Response to Feed Types and Salinity Levels under Laboratory Conditions

Aquaculture of the tropical sea cucumber Holothuria scabra or sandfish is still at a developing stage, especially in the Philippines. In Mindanao, early juveniles of sandfish were successfully produced at the Mindanao State University at Naawan (MSUN) sandfish hatchery for 5 yr now. However, on-site growing of these early juveniles in ocean nurseries often suffered very low survival rates. Two separate laboratory experiments were conducted for 60 d to test for the effects of feed types (Navicula sp., powdered Sargassum, and Sargassum extract) and salinity levels [ambient seawater at 32–35 (as control), 20, 25, and 40 ppt] on the growth, survival, and behavior of 7-wk-old early juvenile sandfish (2–15 mm in length). Juveniles fed with Sargassum extract significantly produced the highest increase in width and length, followed by powdered Sargassum and Navicula sp. with a survival rate of at least 71%. The highest growth rate (GR) and survival were observed with ambient salinity, followed by 40, 25, and 20 ppt. Unusual pale coloration, sluggish movement, and destroyed integument in some parts of the body were observed in some juveniles exposed to lower salinity indication of an unhealthy individual. Overall, Sargassum extract is an ideal feed for sea cucumber juveniles. Low salinity is stressful to early juvenile sandfish and that growth and behavior were adversely affected.