Influence of tank bottom surface on growth and welfare of Senegalese sole ( Solea senegalensis)

Abstract

Tank bottom surface is an important question to take into account in flatfish aquaculture considering the intimate contact that the fish have with it. The most usual materials in aquaculture tank surfaces are inert materials such as epoxy resins or plastics with null porosity, and cement that presents a high alkalinity, roughness and porosity. To improve the cement characteristics, silica fume admixture is usually added in construction industry. The aim of this study was to evaluate the effect of three types of tank bottom surfaces on growth and welfare over a Solea senegalensis population. Moreover, the degree of fin erosion, the appearance of skin lesions and malpigmentation patterns were also monitored. The bottom surfaces tested were plain cement (CE), the same plain cement blended with silica fume (10%) (SF) and epoxy coated surface (EP). Specific growth rate for each bottom surface were compared. The Image Processing Activity Index (IPAI) was used to evaluate the Senegalese sole welfare. Higher SGR and lower IPAI values were obtained in the surface of cement with silica fume, suggesting a higher welfare. The use of plain cement affected negatively the performance of fish, probably due to the high pH and alkalinity of the water in direct contact with fish skin. The null porosity of EP seems to be related to the main cause of higher activity level of fish kept on it outcoming in lower growth. Silica fume that is frequently use to improve the mechanical characteristics of plain cement, also provides benefits in terms of fish welfare.

Environmental enrichment in fish aquaculture: A review of fundamental and practical aspects

“…Ambicolouration or blind‐side hypermelanosis on olive flounder and starry flounder ( Platichthys stellatus ) can be also reduced, or even eliminated, by providing gravel as substrate enrichment in rearing tanks 74,78‐80 . Furthermore, sandy substrates in tanks also play an important role as a prophylactic measure and even for the treatment of skin diseases, for example in Dover sole ( Solea solea ), 72,81 whereas improving plain cement bottoms by blending with silica fume (10%) improves growth, fin erosion, skin lesions and abnormal pigmentation patterns in Senegalese sole ( Solea senegalensis ) 82 . Reiser et al 83 found that natural and artificial substrate enrichment can modulate epigenetic patterns in rainbow trout, affecting global DNA methylation in the brain at the egg and alevin stage, the period during development where the animals are in close physical contact with the substrate.…”

“…74,[78][79][80] Furthermore, sandy substrates in tanks also play an important role as a prophylactic measure and even for the treatment of skin diseases, for example in Dover sole (Solea solea), 72,81 whereas improving plain cement bottoms by blending with silica fume (10%) improves growth, fin erosion, skin lesions and abnormal pigmentation patterns in Senegalese sole (Solea senegalensis). 82 Reiser et al 83 found that natural and artificial substrate enrichment can modulate epigenetic patterns in rainbow trout, affecting global DNA methylation in the brain at the egg and alevin stage, the period during development where the animals are in close physical contact with the substrate. Additionally, cobble substrates provided in concrete raceways can improve fin condition and decrease related infections of rainbow trout and cutthroat trout (Oncorhynchus clarkii).…”

The Use of Sand Substrate Modulates Dominance Behaviour and Brain Gene Expression in a Flatfish Species

“…For example, sand eliminates outbreaks of black patch necrosis on the common sole ( Solea solea ), since sand removes pathogen-promoting dead cells from the fish bodies. Tank substrates provide an opportunity to display burying behaviours in benthic species [ 9 , 10 ]. Moreover, sand reduces respiration and resting metabolic rates in the common sole, showing that this substrate provides a less stressful environment [ 11 ].…”