Control of ectoparasitosis in carp (Cyprinus carpio) induced by Gyrodactylus elegans (Monogenea) with garlic (Allium sativum) and onion (Allium cepa) extracts

One of the constraints in fish disease management in aquaponic systems is related to undesired effects of chemicals on fish, plants and beneficial bacteria. Plant-derived compounds with nontoxic features to fish, plants, and microflora provide an alternative treatment strategy against the harmful pathogens in the aquaponic system. The present study assessed the antiparasitic activity of garlic (Allium sativum) and onion (A. cepa) extracts against Gyrodactylus elegans (Monogenea) in vivo and in vitro, and physiological stress responses in carp, Cyprinus carpio, treated with these extracts in an aquaponics system. Garlic and onion extracts exhibited in vitro antiparasitic activity against G. elegans. The mean survival time of G. elegans in vitro ranged from 30 sec to 6 min depending on the concentration and exposure time both for garlic and onion extracts. For garlic extract EC50 (median effective concentration) was 8.37±4.75 mg/mL in 3 min exposure and for onion extract 4.72±7.10 mg/mL. These concentrations were in vivo tested in carp heavily infected with G. elegans as a single application for 3 min. In vivo treatment of carp with garlic and onion extracts reduced G. elegans found on the skin by 14.4% and 19.8%, respectively. In both treatment groups, the physiological stress response of carp was mild based on the alterations in the secondary stress indicators (hematocrit, plasma glucose, and lactate). The stress indicators of carp returned to normal levels after an hour recovery in freshwater. The antiparasitic potential of onion and garlic extracts may be considered as an alternative treatment to reduce Monogenean infections in aquaponic systems

Anti-parasitic activity of garlic (Allium sativum) and onion (Allium cepa) juice against crustacean parasite, Lernantropus kroyeri, found on European sea bass (Dicentrarchus labrax)

The copepod parasite Lernantropus kroyeri impairs the productivity of European sea bass (Dicentrarchus labrax) culture by leading to a direct infection or as a vector for other disease agents. In current conditions, the parasitic infections in mariculture are usually treated with the chemicals, mainly with the pesticides. However, therapeutic chemical use has potential risks on the overall aquatic environment. Thus, the aquaculture sector needs to find alternative substances to the treatment or prophylaxis of the diseases instead of chemicals. In the present study, in vitro exposure tests were performed to elucidate the effects of garlic (Allium sativum) and onion (Allium cepa) on adult L. kroyeri. Female individuals of L. kroyeri were exposed to different concentrations of garlic or onion juice (20, 40, 60, 80 and 100% of the plant juice) for a specified time. Garlic juice exposure at a ratio of 100% resulted in instantaneous death of all individuals in five minutes. Although the killing time varied by the concentration, garlic juice killed the L. kroyeri females within 30 min even at the lowest concentration. Onion juice had lower killing effect at low concentrations, however, higher concentrations of onion juice killed the female parasites within 60 min. Results revealed that garlic and onion juices had killing effect on L. kroyeri females in a time and concentration-dependent manner. It can be concluded that against parasitic copepods alternative solutions can be developed in aquaculture, using these plant juices with emphasising necessity of further in vivo tolerance tests in fish.Highlights Garlic and onion juices had anti-parasitic effect in vitro on the crustacean parasite, Lernantropus kroyeri found on the gills of European sea bass (Dicentrarchus labrax). After exposure of L. kroyeri to garlic and onion juices, the mortality was time and concentration-dependent. The killing activity of garlic juice for L. kroyeri was stronger than that of onion juice

insight into risks in aquatic animal health in aquaponics

Increased public interest in aquaponics necessitates a greater need to monitor fish health to minimize risk of infectious and non-infectious disease outbreaks which result from problematic biosecurity. Fish losses due to health and disease, as well as reporting of poor management practices and quality in produce, which could in a worst-case scenario affect human health, can lead to serious economic and reputational vulnerability for the aquaponics industry. The complexity of aquaponic systems prevents using many antimicrobial/antiparasitic agents or disinfectants to eradicate diseases or parasites. In this chapter, we provide an overview of potential hazards in terms of risks related to aquatic animal health and describe preventive approaches specific to aquaponic systems

Fish Welfare in Aquaponic Systems : Its Relation to Water Quality with an Emphasis on Feed and Faeces : A Review

Aquaponics is the combination of aquaculture (fish) and hydroponic cultivation of plants. This review examines fish welfare in relation to rearing water quality, fish feed and fish waste and faeces to develop a sustainable aquaponic system where the co-cultured organisms, fish, bacteria in biofilters and plants, should be considered holistically in all aquaponics operations. Water quality parameters are the primary environmental consideration for optimizing aquaponic production and for directly impacting fish welfare/health issues and plant needs. In aquaponic systems, the uptake of nutrients should be maximised for the healthy production of the plant biomass but without neglecting the best welfare conditions for the fish in terms of water quality. Measures to reduce the risks of the introduction or spread of diseases or infection and to increase biosecurity in aquaponics are also important. In addition, the possible impacts of allelochemicals, i.e., chemicals released by the plants, should be taken into account. Moreover, the effect of diet digestibility, faeces particle size and settling ratio on water quality should be carefully considered. As available information is very limited, research should be undertaken to better elucidate the relationship between appropriate levels of minerals needed by plants, and fish metabolism, health and welfare. It remains to be investigated whether and to what extent the concentrations of suspended solids that can be found in aquaponic systems can compromise the health of fish. Water quality, which directly affects fish health and well-being, is the key factor to be considered in all aquaponic systems.peerReviewe