This research used catfish seeds as the tested animal and water hyacinth as the aquatic plant biota. This research used a completely randomized design (CRD) with four treatments of water hyacinth replacement frequency, each of which was repeated four times. The treatments were A). Without the administration of water hyacinth (control), B). Administration of water hyacinth without replacement, C) Replacement of water hyacinth every three weeks, and D). Replacement of water hyacinth every two weeks.
Аннотация научной статьи по строительству и архитектуре, автор научной работы — Lumbessy Salnida Yuniarti, Diniarti Nanda, Famila B. J. Ega Puspita
MATERIALS AND METHODS OF RESEARCH
Похожие темы научных работ по строительству и архитектуре , автор научной работы — Lumbessy Salnida Yuniarti, Diniarti Nanda, Famila B. J. Ega Puspita
1,2 1 0,8 0,6 0,4 0,2 0
Gravel filter constructed on a concrete platform. Water outlet pipe is installed before filling up the filter bed. Space between inner and outer walls must be filled up with pebble of 3–7 mm particle size.
For tank rearing of broodfish valuable feed containing high level of animal protein and other essential materials (fatty acids, vitamins) are necessary. Most suitable feed ingredients for preparation of such type of broodfish feed are fresh (ground) trashfish, mustard oil cake powder, cattle blood, wheat bran, rice polish and vitamin premix used in poultry farming. 2.0–2.5 percent food is sufficient for maintenance of broodfish population in sexually active condition.
6.1.6 Selection of broodfish for spawning
For satisfactory survival in ponds, special pre-and post-stocking treatments are necessary. Following steps are to be taken in pre-stocking management:
Due to high environmental stress resistance and other favorable features of the species, artificial reproduction of African magur is easier than that of other fish. Handling of female and male fish is easy because of comparatively small size. The fish are not sensitive to inaccurate administration of hormone doses. The stress during latency period does not affect the process of ovulation. Lack of sufficient oxygen in water has no adverse effect on ovulation. No special treatment is necessary for elimination of stickiness of eggs. It stops during incubation. Normally there is no harmful fungal infection during incubation, if the water temperature is higher than 24–25°C. It is also easy to separate bad eggs, egg shell and deformed fry from healthy larvae.
6.1.4 Management of broodfish populations
For accurate selection of female for breeding, a small sample of eggs should be taken out from ovary by catheter or sucking with a special narrow tube (canule) fitted with a syringe (Figure 5). Thin empty ink-tubes of ball-point pens can be used for preparation of the canula. Majority of the eggs (more than 90%) should have diameter bigger than 1 mm in the ripe ovary. This method is suggested for selection of broodfish in off-season period or to select fish available for reproduction from young populations (Viveen et al., 1986).