Providing fry for farms in the optimum time and suitable amounts with a high survival is considered one of the success factors of cultured tilapia in Egypt. Therefore, foundation hatcheries near rearing ponds encourage providing seeds before starting the production season in high quality to avoid transportation costs. The transportation of tilapia brood-stock from collection sites to the hatcheries needs to take some precautions to reduce the associated stress during transportation, such as the shock of the transportation means, a small volume of transport tanks or plastic bag, a high density, a decrease in the level of dissolved oxygen (DO), an increase in the total ammonia and carbon dioxide, and the accumulation of metabolic and organic wastes.
The present study was conducted to create a new strategy for increasing the transport efficiency of brood-stock Nile tilapia (Oreoccromis niloticus) using clove and mint oils for 3.5 h. The fish study was exposed to conditions simulating those normally used in transporting. This study was performed in a fish research center of the Arish University. The average initial weight of the brood-stock was 117.07 ± 09.07g (± standard error). The brood-stock was randomly distributed into 10 clear plastic aquaria (30-liter capacity) with a stocking density of one brood-stock/3.75 liter of water. The present study examined two concentrations of clove oil as a deep anesthetic for 5 min. and two concentrations of mint oil as a sedative. It includes five treatments in duplicate, which were: the control group, G1: clove and mint oil at 100 and 20 µL/L, respectively; G2: 100 and 10 µL/L of clove and mint oil, respectively; G3: 50 and 20 µL/L of clove and mint oil, respectively; and G4: 50 and 10 µL/L of clove and mint oil, respectively. Blood samples were taken before transporting from a random sample and after transporting from every group.
Using clove oil as a deep anesthetic agent at a concentration of 100 mg/L for 5 min before transport, thereafter changing the transport water and adding the mint oil at 20 mg/L achieved a high quality of tilapia brood-stock transport, with duration of 3.5 h.
This strategy recorded the best water quality, hematological parameters, and highest SR, followed by the transported brood-stock using 100 mg/L of clove oil and 10 mg/L of mint oil (Table 1 and 2). Decreasing the dose of the pre-deep anesthetic agent (clove oil) to 50 mg/L resulted in decreased transport efficiency. The transported brood-stock without the use of sedative oils has the worst parameters of water quality, blood indicators, and SR that reached 50% after 24 h of the transport.