International Journal of Aquaculture, 2017, Vol.7, No.13, 86-93
91
bamboo (0.90 mg/cm
2
), PVC (0.97 mg/cm
2
) (Gangadhar and Keshavanath, 2008), palm leaf (1.17 mg/cm
2
),
coconut leaf (1.58 mg/cm
2
), bamboo (1.09 mg/cm
2
) and bagasse (1.06 mg/cm
2
) (Keshavanath et al., 2012). Azim
et al. (2002) reported maximum periphyton productivities of 1.01, 1.38 and 1.03 g C m
2
/d for bamboo, hizol and
kanchi substrates respectively. Nutritional quality of periphyton can be quite variable, depending on the
taxonomic composition, type of substrate, ecosystem, fertilization and predation pressure (Azim et al., 2003;
Keshavanath et al., 2012). Protein and lipid content of periphyton grown on bamboo, ambay and leucaena was
24.42% and 2.35%, 22.18% and 1.87%, 21.63% and 1.93% respectively. Azim et al. (2002) estimated 27.19%
crude protein in periphyton developed on bamboo, 14.63% on hizol branches and 18.74% on kanchi (bamboo
shoot), while the lipid content was 5.43% in hizol periphyton and 0.35% to 2.75% in periphyton from bamboo and
kanchi. Periphyton protein and fat could be considered a good source for fish which can satisfy part of their
requirement. Ash content was marginally lower at 11.78% in periphyton from bamboo as against 12.85% and
13.42% of ambay and leucaena. Azim et al. (2002) recorded higher periphyton ash content on hizol (41%) than on
bamboo and kanchi (29%). In the present study, NFE accounted for 53.28-54.44% (Table 4). Ledger and Hildrew
(1998) reported 29-33% carbohydrate in periphyton developed on stones. Nielsen et al. (1997) observed that the
extra-cellular polymeric substances in biofilms are responsible for 50-80% of total organic matter and therefore,
large amounts of carbohydrate, which explains the high proportion of carbohydrates in periphyton. The gross
energy values were 356.37, 342.86 and 343.28 kcal/100g for periphyton from bamboo, ambay and leucaena
substrates. These values are lower than those recorded in periphyton associated with hizol and kanchi (454
kcal/100g) by Azim et al. (2002). Bamboo periphyton had higher chlorophyll-a (39.59 µg/cm
2
) than that of ambay
(35.15 µg/cm
2
) and leucaena (32.76 µg/cm
2
). The difference in values could be attributed to both the number and
species of algae present. Phytoplankton population of periphyton from the three substrates belonged mainly to the
families Chlorophyceae, Cyanophyceae, Bacillariophyceae and Chrysophyceae as reported in earlier studies
(Gangadhar and Keshavanath, 2008; Tortolero et al., 2016). There was significant difference in the abundance of
periphyton zooplankton, the numbers being 2 and 3 times higher in bamboo periphyton than that of ambay and
leucaena. This could have influenced fish growth.
Fish showed the best growth in bamboo treatment, being significantly superior to not only the control, but also the
other 2 substrate treatments (Table 5). Jaraqui growth under the 3 substrates (bamboo, ambay and leucaena) was
higher by 76.65, 53.55 and 25.41% respectively over the control. Azim et al. (2002a) obtained 66-71% greater
carp production with substrates, whereas Gangadhar and Keshavanath (2012) recorded 37.74-43.56% higher
production. Keshavanath et al. (2012) reported 35-87% higher production of common carp using 4 bio-substrates.
Bamboo provides a better surface structure for periphyton species to attach to, or might leach nutrients beneficial
to periphyton growth (Keshavanath et al., 2001). This might be the reason for the superior growth of fish under
bamboo treatment. Earlier studies have also shown the superiority of bamboo as a substrate in fish culture (Hem
and Avit, 1994; Azim et al., 2002). Keshavanath et al. (2002) who obtained 41-75% increase in fish growth in
non-fed substrate based tanks opined that substrates reduce the need for artificial feed and therefore, can be
considered as an alternative to feeding in the culture of herbivorous fish.
The results of the present study show that 25 to 76% higher growth of jaraqui can be obtained in non-fed
substrate-based tank culture, compared to the control without substrate. Further, the superiority of bamboo as a
substrate is discernible. The findings have economic significance.
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