First data on rabbit dung as a water fertilizer in tropical fish culture and its effect on the growth of Oreochromis niloticus (Teleostei, Cichlidae)

The influence of rabbit dung on water quality, plankton occurrence and Nile tilapia growth (Oreochromis niloticus) was studied. pH and total alkalinity increased, dissolved oxygen concentration decreased but not below the critical level whilst the nitrogen parameters were not affected in a significant way. An important increase of plankton was recorded and was reflected in a decrease of transparency: the phytoplankton density was 2.7 times that of the controls. Tilapia growth rate in the manure treatments was 5.1 times that of the control group; no significant difference in survival rates was observed.     

Alternative life-history traits associated with reproduction in Oreochromis mossambicus (Pisces: Cichlidae) in small water bodies of the eastern Cape,South Africa

Synopsis Four wild populations of Oreochromis mossambicus were investigated to examine the effects of environmental factors on reproductive biology in contrasting habitats. Age at maturity, spawning-season length, spawning frequency, clutch size and nesting behaviour were influenced by the prevailing conditions for feeding, breeding and refuge. Even under a temperature regime that approached lethal limits during winter, and erratically fluctuating water levels, O. mossambicus demonstrated an ability to adopt a precocial life-history style in some habitats. In more hostile water bodies an increasingly altricial style was followed.     

The life-history traits of widespread freshwater fish species: the case of Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) in water bodies at the southern limits of distribution

The Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) is a widespread Eurasian cyprinid freshwater fish. Although numerous studies have investigated the species’ life history traits across its main native range of distribution, little is known from water bodies located beyond the southern limits of the latter, especially where the species has been introduced. Between July 2010 and April 2011, a total of 949 R. rutilus specimens was collected from Porsuk Reservoir (NW Turkey), and life-history traits of age, growth, fecundity and egg size were studied and compared to six other R. rutilus populations (including Caspian Roach R. r. caspicus) from the southern limits of distribution. The Porsuk population was characterised by relatively shorter lifespan, slower growth and lower fecundity. These findings support previous studies emphasising the importance of local environmental factors in shaping the life-history traits of widespread fish species. These must be taken into consideration especially in view of the potential value of R. rutilus as an economic resource for in-land fisheries.     

Reverse translation: effects of acclimation temperature and acute temperature challenges on oxygen consumption,diffusive water flux,net sodium loss rates,Q10 values and mass scaling coefficients in the rainbow trout (Oncorhynchus mykiss)

Journal of Comparative Physiology B - Our understanding is limited on how fish adjust the effective permeability of their branchial epithelium to ions and water while altering O2 uptake rate (MO2)...