Evaluation of the application of seaweed (Eucheuma cottonii) extract as fish anesthetic agent

Fish anesthetics have been a long time applied for handling and transporting fish. Eucheuma cottonii has been well known as antibacterial, antioxidant, and anti-cancer, and it is possible to be used as fish anesthetics due to the content of flavonoids and saponins. The pharmacologic properties of E. cottonii are very well documented. This study aimed to investigate the anesthetic potency of E.cottoni extract including its induction time, recovery time, the power of anesthetic, and the phenol absorption by fish, as well as determining their mathematical models. This study was conducted by immersing fish in solutions of varying concentrations of E. cottonii (30, 40, and 45% v/v). The immersed fish were then observed for anesthetic induction time, anesthetic recovery time, power of anesthetics, and phenol absorption of the fish. The results of the experiment show that the E.cottonii extract could anesthetize Oreochromis niloticus with the best concentration of 45% (v/v) with an induction time of 3.00 ± 1.41 min and recovery time of 3.22 ± 1.62 min. The induction time followed the exponential model with the equation y = 936449e − 0.282 × (R² = 0.9993). The recovery time followed the exponential equation with the equation y = 0.0208e0.1075 × (R² = 0.9025). The anesthesia power followed the logarithmic model for induction time with the equation y = − 541.5ln(x) + 2135.7(R² = 0.9025) and exponential model for recovery time with the equation y = 0.0165e0.1243 × (R² = 0.9738). This study shows that E. cottonii could be used as an anesthetic in Oreochromis niloticus. And that at a concentration of 45% v/v, E. cottonii could produce an anesthetic effect with a duration of 4 h. The model of phenol absorption was pseudo-second-order for all concentration.