Growth performance and digestibility
The water hyacinth is incorporated in the feed at different concentrations
viz., 20, 40, 60, 80 and 100%. The mean weight gain of the fishes fed with control was 138.73±0.06 g which is higher than that of the fishes fed with Control (131.78±0.11 g). The mean weight gain of fishes fed with other concentrations like 60, 80 and 100% showed decreasing trend.
With regard to the Average Daily Growth the fishes fed with 20% showed 1.54 g which is not similar to 60% and 100% when compared to other treatments. High Survival is seen in 20% and lower in 80%. Bio growth performances of GIFT Tilapia fed under different inclusion level of water hyacinth feed is given in Table 4. Mean body weight of GIF Tilapia fed with different inclusion levels of water hyacinth is shown in Fig 1.
Selvaraj et al., (2021) discovered that water hyacinth could replace up to 20% of fish meal in tilapia diets without compromising growth or feed utilisation.
Azubuike et al., (2016) discovered that water hyacinth may replace up to 30% of the fish meal in tilapia diets, however higher levels of water hyacinth resulted in slower growth.
Nartey et al., (2000) discovered that water hyacinth may substitute up to 40% of the fish meal in tilapia diets, but that higher levels of water hyacinth resulted in higher levels of oxalates in the fish.
In the present study the fishes in the treatment T1 (20% WH) showed higher mean body weightfollowed by T3 (60% WH), T2 (40% WH) and C1 (0% WH). The lowest mean final body weight was seen in T5 (100% WH). T4 (80% WH) showed lower performance than T1, T2 and C1.
El-Sayed (2003) discovered that water hyacinth meal, at levels up to 20%, has a favourable influence on fish growth. However, higher levels of inclusion (30% or above) might be detrimental to growth.
Emshaw et al., (2023) discovered that fermented water hyacinth can boost fish development performance. This is most likely due to the fact that fermentation reduces the fibre level of water hyacinth, making it more digestible for fish.
Bake et al., (2015) discovered that the type of fish used can influence the responsiveness to water hyacinth diets. Omnivorous fish, such as Nile tilapia, appear to outperform herbivorous fish, such as common carp, on water hyacinth diets.
Riechert and Trede (1977) published the results of a preliminary indoor laboratory study on the feeding of water hyacinths to grass carp conducted in Germany. They discovered that feeding the fish water hyacinth leaves resulted in a feed conversion ratio (FCR) of 1.54.
Paiva et al., (2009) studied the growth of Nile tilapia (
Oreochromis niloticus) fingerlings fed diets with varying quantities of water hyacinth leaf meal in Brazil. They discovered that fish grew well on diets containing up to 25% water hyacinth leaf meal but that higher amounts resulted in lower growth and survival.
According to
Akter et al., (2014), rohu fingerlings fed a 40% water hyacinth diet showed no negative effects on their health or behaviour.
Akter et al., (2019) discovered that rohu (
Labeo rohita) fingerlings fed a 40% water hyacinth diet grew faster than rohu fingerlings fed a 20% water hyacinth diet.
Abol-Munafi et al., (2012) found that meals containing water hyacinth had a worse apparent digestibility of dry matter, crude protein and gross energy than diets containing fish meal. However, the water hyacinth’s digestibility increased after it was fermented. In contrast to 45% in unfermented water hyacinth, crude protein apparent digestibility in fermented water hyacinth was 56%.
According to
Abdel-Fattah and Mamdouh (2008), the apparent digestibility coefficient of carbohydrate in water hyacinth and fish diets was 60.56%. This number was much lower than the apparent carbohydrate digestibility coefficient in fish meal, which was 80.44%. According to
Wee (1991), the apparent digestibility coefficient of carbohydrate in fermented water hyacinth is 76.8%. This figure was much greater than the apparent carbohydrate digestibility coefficient in unfermented water hyacinth, which was 56.0%. According to
A-Rahman Tibin et al., (2012), the apparent digestibility coefficient of carbohydrate in water hyacinth-included fish diets dropped as the amount of water hyacinth in the diet rose.
These results were in accordance with the present study which showed that water hyacinth at 20% replacement of fish meal has higher growth performance when compared to control and other treatments. These studies suggest that the apparent digestibility of water hyacinth included fish diets can be improved by processing the water hyacinth. However, even with processing, the digestibility of water hyacinth is still lower than that of fish meal.
The present study showed better growth performance in 20% replacement of fish meal. The proper handling and preparation of feed can also contribute to the positive result. The replacement showed no negative impact on the fish.
Economic analysis
The economic analysis of combination diet of water hyacinth incorporated diets were studied for the following variables like seed cost, feed cost, total cost, cost of production/kg, total amount realized, net income, net income/kg. The values for the calculated variables were shown in Table 4. The cost of production/kg was seen higher inC1 (Rs.141.44) and the lowest cost of production was seen in T5 (Rs. 109.63).
Statistical analysis
The statistical analysis like Student’s t test, Duncan multiple range test (
Duncan, 1955), One way ANOVA was done with the help of Microsoft excel and SPSS 16.0. Students ‘t’ test affirmed that mean growth value showed significant difference between different inclusion level of water hyacinth.
One way ANOVA of the data collected affirmed that among different inclusion level of water hyacinth diets, mean growth values showed significant different between the test diet. Similarly, time bound variations also showed significant difference.