Use of rice straw as substrate for periphyton-based fish culture | |
| Author | Rai, Sunila |
| Call Number | AIT Diss. no.AQ-07-11 |
| Subject(s) | Periphyton--Bangladesh Periphyton--Thailand Straw Carp fisheries |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Technical Science in Aquaculture and Aquatic Resources Management, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AQ-07-11 |
| Abstract | This study, consisting of five experiments, was conducted to assess the potential of using rice straw as periphyton substrates for freshwater fish culture. Experiments one and five were carried out in the Asian Institute of Technology, Thailand, and experiments two to four in the Bangladesh Agricultural University, Mymensingh, Bangladesh. Experiment one was conducted to determine the appropriate loading level of rice straw in 5-m² fertilized cement tanks without stocking fish. There were six different loading rates of rice straw each in triplicate, that-is, 625, 1,250, 2,500, 5,000, 10,000 and 20,000 kg ha⁻¹ (dry matter basis). The result showed that the loading rate of 625 kg ha⁻¹ was best. Water quality deteriorated with increased loading rates of rice straw. Periphyton grown on rice straw surface alone could contribute a maximum fish production of 1,825 kg ha⁻¹ y⁻¹. Experiment two was conducted to optimize the loading number of rice straw mats in fertilized 40-m² ponds stocked with rohu (Labeo rohita), catla (Catla catla), mrigal (Cirrhinus mrigala), common carp (Cyprinus carpio) and silver carp (Hypophthahnichthys molitrix). There were six treatments in triplicate each: a) no rice straw mats (control); b) using rice straw mats to cover pond dikes; c) suspending one (1 x 625 kg ha⁻¹) rice straw mat in water column; d) suspending two (2 x 625 kg ha⁻¹) rice straw mats in water column; e) suspending three (3 x 625 kg ha⁻¹) rice straw mats in water column; and f) suspending four (4 x 625 kg ha⁻¹) rice straw mats in water column. The results showed that three straw mats per pond gave the highest total weight gain (0.44 ± 0.07 t ha⁻¹ 90 days⁻¹) among all treatments (P<0.05). In experiment three, plankton-based carp polyculture system was compared with two periphyton-based carp polyculture systems using rice straw mats (3 straw mats per pond, 3 x 625 kg ha⁻¹) or kanchi (390 bamboo side shoots per pond) as substrates in fertilized ponds. Rice straw and kanchi treatments gave 38% and 47% higher total weight gains than that in the control (P<0.05), due probably to periphytons and bacterial biofilm from substrates. The rice straw treatment appeared to be more economic than the control and kanchi treatment. In experiment four, two periphyton-based carp polyculture systems using rice straw mats (3 rice straw mats per pond, 3 x 625 kg ha⁻¹) and kanchi (390 bamboo side shoots per pond) as substrates were compared in ponds with supplementary feed. The results showed that fish growth and weight gains did not vary between the rice straw and the kanchi treatment except catla (P>0.05). Daily and total weight gains of catla was 48 and 32% higher in the kanchi treatment than in the rice straw treatment (P<0.05). However, the rice straw treatment gave more profit than the kanchi treatment. Experiment five was conducted in aquaria to determine the nibbling frequency of rohu, catla, mrigal, common carp and silver carp on kanchi infested with periphytons, in feeding and non-feeding systems. Web camera and video camera were used to observe fish nibbling behavior for 12 hours (07:30 - 19:30 h). Rohu, catla and common carp nibbled on the kanchi, while mrigal and silver carp did not. Nibbling frequency of rohu and catla was significantly higher in the non-fed treatment than in the fed treatment (P<0.05). The present study has demonstrated that rice straw which is widely available low-cost material in South Asia can be used to increase fish production through the development of bacterial biofilm and periphytons in the periphyton-based aquaculture system. The technology is simple, cost effective and appropriate for resource poor farmers. However, further research is needed on design of rice straw mats so that rice straw can be held longer in the water column, on techniques to supply periphytons and bacterial biofilm grown on rice straw consistently, and on optimization of fertilization regimes, supplemental feed, stocking density as well as species combinations. |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AQ-07-11 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Yang, Yi;Bart, Amrit; |
| Examination Committee(s) | S. L. Ranamukhaarachchi;Verdegem, Marc Charles Jean; |
| Scholarship Donor(s) | Third world Organization for Women in Science (TWOWS);Aquaculture Collaborative Research Support Program (ACRSP); |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2007 |