Aims: Information on ichthyoplankton is an important tool in determining reproduction periods that if associated to environmental variables. The abundance and distribution of ichthyoplankton and their relationships to some environmental variables of the water in Lake Buyo were analyzed. Preferred microhabitats for spawning, dispersion and nursery were also verified.
Place and Duration of Study: The study was conducted monthly from April 2019 through September 2019 in lake Buyo.
Methodology: Acylindro-conical net (500 µm in mesh opening size, 50 cm in mouth diameter) and stream net (7 mm in mesh opening size) were used.
Results: During the study period, the very lowest densities of eggs (1-2 ind/10 m3) and larvae were recorded in sites (S3 and S8) located relatively far from shoreline and the highest (186-724 ind/10 m3) in sites located near shoreline. The sites closed to littoral were identified as spawning areas by fish species during study period and sites located in deep water are not spawning sites. No significant difference between seasons was observed for each sampling site.
Conclusion: Eggs and larvae distribution in Lake Buyo was strongly influenced by water depth, water temperature, dissolved oxygen, percentage of gravel, percentage of coarse sand and proportion of very fine sand.
Aims: The Tanoe-Ehy swamp forest (TESF) is a freshwater swampy area characterized by seasonal variation of environmental parameters and fish diversity. So, the aim of this study was to analyze seasonal variations of growth parameters and condition factors of the three abundant species.
Methodology: Specimens were collected by using gill nets and fyke nets, measured and weighed. Length-weight relationship (LWR), Fulton’s condition (KF) and relative condition (KR) factors were analyzed from Standard Length (SL) and body weight (BW).
Results: The Standard Length of Clarias buettikoferi, Thysochromis ansorgii and Parachana obscura varied between 9.50 and 29.30 cm, 4.60 and 11.50 cm, 10.70 and 29.30 cm, respectively. The growth type of population was allometric negative for C. buettikoferi and P. obscura and isometric for T. ansorgii. In terms of seasonal variation, C. buettikoferi females and P. obscura specimens exhibited isometric growth in dry seasons (DS) against a negative allometric growth in flooded seasons (FS). In contrast, female and combined sex specimens of T. ansorgii showed positive allometric growth in DS and isometric growth type in FS. KR varied between 0.76 and 2.02 and was significantly higher in FS than in DS, indicating a state of well-being during flooded seasons in the 3 species.
Conclusion: There was a significant relationship between length with weight and both condition factor for the three species. This study provided the first data about fish body measurements in the TESF and concluded that LWRs and condition factors of the three fish species were strongly influenced by seasonal variations in hydrological conditions.
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