|
|
Proximate control of sexual dimorphism in livebearer Poecilia wingei
Farkačová, Klára ; Kratochvíl, Lukáš (advisor) ; Slavík, Ondřej (referee)
The effect of 17α-methyltestosterone a 17β-estradiol on sex of livebearer fish Poecilia reticulata and P. wingei was studied. Solution of 2.5 mg testosterone was added in the aquarium the first and fifteenth day after delivery of new fry. Estrogen was administered in food to gravid females (400 mg per 1 kg food). Sex of all individuals was determined in one, two and three months. Administration of neither testosterone nor estrogen caused sex reversal; in the second case reproduction of almost all females was stopped.
|
|
|
Comparison of selected characteristics of fertility in different lines of fish Poecilia reticulata.
JUNEK, Jaroslav
The aim of the study was to compare selected characteristics of fertility in different lines of fish Poecilia reticulata. Among the selected characteristics of female fertility were the length and number of births. The experimental work was conducted in the period from March 2013 to February 2014. Were observed in three lines. Fish tested were deployed in 15 pairs from each line into three tanks, which is then reproduced. Length of females was assessed at birth and number of births. The results of this work show that while the lines Magdalenas and Wingei-Endleri was the influence of the number of female births indicated as statistically significant, in line Inirida as statistically significant was not approved.
|
|
|
Do humic substances reduce nitrite toxicity to fish?
VANĚČEK, Miloslav
The aim of this work was to verify the hypothesis that humic substances reduce toxicity of nitrite to fish. Under laboratory conditions, tests of acute toxicity were performed on aquarium fish: zebrafish (Danio rerio) and guppy (Poecilia reticulata). Fish were exposed to nitrite in the presence or absence of humic substance HS 1500. Nitrite was dosed as NaNO2. Preparation Dupla Cur (manufacturer Dohse Aquaristik KG) was a source of the humic substance (HS 1500). The preparation was tested in two different concentrations: 0.5 ml.l-1 and 1 ml.l-1. Toxicity tests were performed according to Czech standard ČSN EN ISO 7346-2. Based on the observed mortality in the acute toxicity tests, 96hLC50 values of sodium nitrite for selected species were calculated in the presence or absence of the tested preparation Dupla Cur. Tests on zebrafish showed a positive effect of Dupla Cur preparation at a concentration of 0.5 ml.l-1 on decreasing of nitrite toxicity. In this case 96hLC50 value was about 73 % higher than the value found in the test where the preparation was omitted. At a concentration of 1 ml.l-1 of the preparation a significantly positive effect was not observed. In the tests on guppy, an effect of Dupla Cur preparation on the toxicity of sodium nitrite was not observed. The tested humic substance does not have the same effect on all fish species. The effect depends on its concentration in the water.
|
|
|
Influence of water temperature on toxicity of free ammonia for fish and on amount of ammonia produced by fish
MECKO, Jozef
Determination of acute toxicity of free ammonia for fish in dependence on water temperature and determination of production of ammonia by fish in dependence of water temperature It was made a test of acute toxicity on akutní toxicity on Poecilia reticulata according to ČSN EN ISO 7346-2 and determination of acute lethal toxicity of substances for fish. Next was made test on excretion of ammonia by common carp in different temperatures of water. Fish were divided after a two pieces into basins.The water temperature was kept in basins on two level. Next test was realized in a similar way with a difference, that an amyloid gel with an addition of NH4Cl was aplicated by a probe to the digestive tract of fish. To control fish were aplicated the amyloid gel without an addition of NH4Cl. It was observed concetration of ammonia in water and the fish were bleeded to set haematocrit and biochemical values. On grounds of these values will be analyzed production of ammonia by one species of fish in dependence on water temperature.
|
guest ::
