Background:
Physical stress in fish may lead to many undesirable neuro-hormonal responses such as the changes in circulating catecholamines and corticosteroids, resulting in osmoregulatory disturbance, altered metabolism, haemato-biochemical and deviated immune function, decreased disease resistance, and reduced reproductive performance. Mortality and disease occurrence are the immediate visible impact of severe stress on fish during handling and transportation. Normally, anesthetics are used to immobilize and reduce metabolism in fish, thereby reduce stress in fish during handling for experimental and commercial purpose. There are several chemical anesthetics available for aquatic animals but not free from adverse health effects, some of them being carcinogenic necessitating long withdrawal period (waiting period) before release in the environment or sold for human consumption. In previous works, pure essential oils (mainly clove oil) were explored as anesthetics mainly for experimental purposes where the essential oils were diluted to 1:10 (v/v) with absolute ethanol before use in fish tanks. This alcohol mixture of essential oils serves the purpose in small volume of water needed for experimental anesthesia (for few minutes). However, for sedative effect (stage 1 anesthesia) required during long transportation with larger water volume, this alcohol mixture does not work. Alcohol being a volatile solvent will evaporate out leaving the oil floating on the surface with time. Required quantity of essential oil having small amount of alcohol drawn from the stock solution (1:10 ratio) when added to larger volume of water where sedative effect is needed for longer duration, emulsion may break due to phase separation (as alcohol is volatile solvent and diluent volume is large). Further, to maintain the dispersion in larger volume of water, larger quantity of alcohol with additional risk to the subject animal is required which will also increase the cost.:
Technology Details:
CIFRI Fish Tanavhari developed by ICAR-CIFRI includes polymeric carriers to produce stable water dispersible formulations of plant essential oils selected from eugenol containing or non-eugenol containing group of plant essential oils which are free from solvents and can be applied in larger volume of water for instant dispersion of the oils, for quick induction of anaesthesia (stage 3) in the fishes and their quick recovery without any harmful effect and mortality. The water dispersible formulations of the oils at a lower dose are able to induce quick sedation in the fishes and maintain the effect for a longer period of time (up to 15 hrs in artificially aerated condition). Regular change of water in every six hour (normal water, no artificial aeration) and addition of formulation can keep the fishes sedated for 24 hrs. The extended sedation duration with the use of essential oil formulation will provide much needed stress-free transportation of fishes (especially the cat fishes). Fishes transported to a distance covered in 24 hrs when released to natural water, no or very little mortality (<2%) are recorded due to additional benefit of immune stimulation and antimicrobial effect of the essential oil preventing secondary infection, besides the anesthetic effect.:
Advantages of CIFRI Fish Tanavhari • Easy to apply in water:
• Small quantity required:
• Quick dispersion in water:
• Quick anesthesia/sedation:
• Quick recovery, no mortality, no adverse effect:
• Plant extract based formulation:
• Eco-friendly product:
User guidance:
• Dose: 25-40 µl/l or 3-5 drops in 5 l of water for sedation. :
• For longer duration, replace water after every 6 hrs and add half of the initial dose. :
• 125-200 µl/l or 13-20 drops in 5 l of water for anaesthesia. :
• Shake well before use.:
• Keep tightly capped after use.: