Growth and dietary utilization in goldfish (Carassius auratus Linn.) fed diets formulated with various local agro-produces

Partha Bandyopadhyay a, Saroj K. Swain b, Snehasish Mishra c

Institute of Freshwater Aquaculture (Indian Council of Agricultural Research), Kausalyaganga, Bhubaneswar 751002, Orissa, India c Kader Exports Pvt. Ltd., Gollalakoderu, Palakoderu Mandal, Bhimavaram 534 202, West Godavari Dist., AP, India

Received 1 October 2002; received in revised form 15 June 2004; accepted 16 June 2004

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Abstract

During a 60 d feeding trial, goldfish (Carassius auratus) measuring 1.66 ± 0.02 g by weight and 4.2 ± 0.02 mm by length were fed diets containing 23.34%, 26.21%, 29.30%, 32.24% and 42.53% crude protein in Feeds I through V respectively. The four formulateddiets (Feeds I, II, IV and V) contained groundnut oil-cake, wheat bran, soybean meal, fish meal, cod liver oil, vegetable oil and vitamin–mineral mixture with tapioca as binder and a commercially-available diet (Feed III) procured from the market. All the feeds were dispensed twice daily at 4% body weight. Results revealed that the growth (in terms of net weight gain and specific growth rate) and dietary utilisation (in terms of feed conversion ratio, protein retention efficiency and energy retention efficiency) were observed to be significantly greater (p 6 0.05) in Feed V which contained 42.53% protein followed by Feeds IV, I, II and III, and 7.58%, 6.11%, 6.63%, 7.86% and 7.91% lipid in Feeds I through V, describing clearly the role of a combination of protein and lipid in the diet for growth and feed utilisation. Lowest growth and dietary utilisation was observed in Feed III (the commercial diet). The alkaline and acid phosphatase activities in liver, gill and intestine as also the RNA:DNA ratio in the muscle tissues were greatest in fish fed Feed V, which indicated best growth. It was thus concluded that a protein content of 40–45% in the diet of young goldfish could significantly enhance growth and dietary utilisation. 2004 Elsevier Ltd. All rights reserved.

Keywords: Diet; Crude protein; Feed ingredients; Phosphatase; RNA:DNA; Carassius auratus

1. Introduction

Ornamental fishes are often referred as "living jewels" due to their color, shape, and behavior. They arepeaceful, generally tiny, attractively coloured and could be accommodated in confined spaces. Modern ornamental fish culture and breeding operations, have become

vertically and horizontally intensified, necessitating a continuous supply of nutritionally balanced, cost-effective diets that provide all the essential nutrients to the fish. The application of artificial feed in fish culture is the most expensive input and therefore the supply of quality feed under various environmental conditions is necessary (Sarkar, 1997). Growth is one of the important criteria

for brood stock development, and market price of fish is related to growth. The two main constraints with regard to commercial feeds are their price and lack of availability of species-specific feeds. If feeds are available, considerable variation exists in their price and efficacy (Ako et al., 1997, 1998a,b; Ako, 1999). Cyprinids are the most extensively cultured fish in the world (Anon, 1999). Goldfish (a modified variety of Cyprinus

carpio) could be used as an ideal model for nutritional studies in larval and juvenile cyprinids. It has traditionally been raised in fertilised ponds and fed prepared diets. As culture practices continue to intensify, these species would depend extensively on prepared feeds. However, its nutritional needs are largely unknown. A wide range of feeds is available to feed goldfish in aquarium, but the cost does not make their use economical (Forster, 1998). According to Tacon (1993), feed ingredients such as rice bran, oil cakes, fish meal and other sources which have been used in traditional aquaculture as conventional feed can meet the nutritional requirements of culturable species. Quality feed plays an important role in value addition to commercial goldfish by enhancing their growth, colouration and general health. The market for ornamental fish is increasing (Anon, 1999). To cater to the demand of quality feed for these species, a number of commercial feeds are available in the market. Feed formulation for goldfish is yet to be standardised. As a common practice in India, commercial production of aquarium fish depends essentially on pelleted/granular form of shrimp/prawn feed. Ako (1999) compared all the formulated feeds for aquarium/ coloured fish available in the global market with their retail prices. Species and region-specific formulated feeds face various market constraints, including a (10–60 times) greater price compared to conventional aquaculture feeds, price variability and availability only in 0.5 kg packages. By comparison, conventional aquaculture feeds have been available in 22 kg packages. These constraints have discouraged aqua-feed manufacturers interested in commercial production of species-specific feed. For this reason, sufficient work and comparisons on feed performance have not been done and hence, sufficient information on species-specific, formulated feed has been unavailable. Ingredients from plant proteins (e.g., Spirulina, soybean and alfalfa meals) and fibre are incorporated into diets for goldfish, koi and herbivorous fishes (e.g., certain catfishes and chichlid species) (Chapman, 2000). However, many of these feeds seem to lack popularity due to their cost and inability to satisfy the nutritional requirements of the concerned/target species. Moreover, these feeds apparently do not result in consistent growth that result upon continued use. To cite an instance, the commercial feed used in the present study claims a crude protein content of a minimum of 46% but was determined to be 29.3%. In the current study four formulated diets were prepared using various local agro-produces. Two had crude protein contents lower than the commercial feed (Feeds I and II) and two higher (Feeds IV and V), mixing them in suitable proportions. The range of crude protein content in the aqua-feeds selected for the present study (20–45%) was based on existing information (Mousseau, 1988; Pandian, 1989; Ako, 1999; Yanong, 1999). Keeping these aspects in view, the present study was designed to prepare ornamental fish feeds with different levels of protein, accommodating as many locally available agro- (primary industrial) byproducts and to compare the effect.

1.1. Material


Goldfish juveniles (80 d old) obtained from the ornamental fish culture farm of Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, India had an initial measurement of 1.67 ± 0.02 g and 55.20 ± 0.02 mm. Fish were released into glass jars (90 · 45 · 45 cm3; 182.25 l capacity) after acclimatising to prevailing laboratory conditions of water temperature (25–27 C) and pH (7.6–8.0). Studies were conducted at room temperature (24.9–32.8 C) for 60 days during June to August 2000.

1.2. Methods

1.2.1. Preparation of experimental diets

The four prepared diets (Feeds I, II, IV and V) were formulated using locally available feed ingredients as shown in Table 1. Sixty grams of tapioca flour was boiled over a gas stove at 100 C with 450 ml water and the ingredients were mixed with it. Dough was prepared and the feeds were pelleted separately with local-made (Ludhiana, India) hand pelletiser for preparation of a kg feed. The pellets were dried in a thermostatic oven (M/s Modern Industrial Corporation, Mumbai, India) at 37 C to less than 10% moisture (Keshavanath and Renuka, 1998; Bazaz and Keshavanath, 1993) and stored in airtight jars at room temperature. The proximate composition of all four prepared diets and one commercial (as per laboratory analysis report) diet are detailed in Fig. 1. Feed III ( TOKYU procured from the local market at Bhubaneswar, Orissa, India) contained an ingredient composition of cuttle fish meal, shrimp meal, wheat flour, spirulinar protease, thiamine, riboflavin supplement, soybean meal, vitamins A, C, D3, K, B1, B2, B6 and B12; minerals Zn, Co, Fe, Mn, Cu, P, Mg, and p-amino benzoic acid, and proximate composition of crude protein, min. 46%; crude fat, min. 6%; crude fibre, max. 5%; moisture, max. 10%; crude ash, max. 12% and nitrogen-free extract, 20% (as per ingredient label).

1.2.2. Studies on growth 

The experimental setup consisted of 15 cylindrical glass jars (triplicates of each treatment) of 10 l capacity (radius 22 cm and height 30 cm) with continuous aeration. Each jar was stocked with six fish. Water quality was monitored at weekly intervals following the methods provided in APHA-AWWA-WPCF (1998). Fishes were fed twice daily at 08.00 and 16.00 h at 4% body weight (Chapman, 2000) in two equal installments. The unutilised/leftover feed orts were siphoned out 2 h after dispensing the feed into the jars. Fifty percent of the water was replenished daily with aged ground water. The wet weight of the fish were recorded every 15 days with an electronic balance (Adair Dutt Instruments Pvt. ltd., Kolkata, India) and feed quantity was readjusted after every weighting period of 15 days. Fish were terminated through overdose anaesthetisation by MS222 (Sigma chemicals) at the end of the experiment, and stored at 20 C until analysis.

1.2.3. Proximate analyses 

Moisture content was determined by drying the feeds in an oven at 110 C for 24 h. Crude protein content (Total Kjeldahl Nitrogen · 6.25) of the diets and ingredients were determined by the micro-Kjeldahl method (AOAC, 1990). Crude lipid contents were estimated by the Soxhlet extraction method using petroleum ether (boiling point 40–60 C) in the electro-thermal Soxhlet apparatus. Ash content was estimated by incinerating samples in a muffle furnace at 400 C for 12 h (AOAC, 1990).Two hours after feeding, the left-over feed was initially siphoned out and equal amount of water was replenished. For faecal matter analyses, pooled faecal matter was collected into petridishes from the bottom of the jars at every 2 h by the help of a pipette (Singh, 1989). The collected material was stored at 20 C (Sundaryono et al., 1996). The collected material was dried in an oven (M/s Modern Industrial Corporation, Mumbai, India) at 55 C, ground and preserved in airtight containers. Two hours after feeding, the left-over feed was initially siphoned out and equal amount of water was replenished. For faecal matter analyses, pooled faecal matter was collected into petridishes from the bottom of the jars at every 2 h by the help of a pipette (Singh, 1989). The collected material was stored at 20 C (Sundaryono et al., 1996). The collected material was dried in an oven (M/s Modern Industrial Corporation, Mumbai, India) at 55 C, ground and preserved in airtight containers.

1.2.4. Biochemical analyses

DNA (Deoxy-ribo Nucleic Acid) and RNA (Ribo- Nucleic Acid) contents in the striated muscle tissue collected from below the dorsal fin ray area were estimated as per the scheme given by Dagg and Littlepage (1972). The ACP activity was determined following the method of Bramley (1974) and ALP activity by Rosauki (1993).

2. Results and discussion

The water quality during the study period remained in the following ranges: pH, 7.42 ± 0.21 to 7.52 ± 0.20; alkalinity, 135.25 ± 9.56 to 140.25 ± 3.45 ppm; dissolved oxygen, 4.7 ± 0.5 to 5.6 ± 0.4 ppm and total ammonia, 0.27 ± 0.05 to 0.36 ± 0.03 ppm. The proximate composition of ingredients used for preparing experimental feeds is detailed in Table 1. The crude protein percentages on dry matter basis of the experimental feeds were 23.34, 26.21, 29.30, 32.24 and 42.53 in Feeds I, II, III, IV and V, respectively. The crude lipid percentages similarly were 7.58, 6.11, 6.63, 7.86 and 7.91, respectively (Fig. 1). The ash content (11.05%) in Feed V was greatest. The gross energy, protein/energy ratio and cost of each feed in $US are detailed in Table 2. Growth in

terms of net weight gain was greatest (36.02 ± 0.04 g) in fish fed feed V and least in feed III (25.55 ± 0.32 g) during the study period (p 6 0.05) (Table 3; Fig. 2). The NWG, SGR and FCR were also greatest in case of fish fed feed V (26.02 ± 0.08, 2.13 ± 0.006 and 1.94 ± 0.01, respectively, Table 4). Similarly, the PRE (51.87 ± 0.42) and PER (1.74 ± 0.02) were greatest in fish fed Feed I and least in fish fed Feed V (1.21 ± 0.01) and fish fed Feed III (28.61 ± 0.95), respectively. Similarly, ERE was greatest in fish fed Feed V (74.25 ± 0.14) and least in fish fed Feed II (48.62 ± 0.12). Faecal matter proximate analysis revealed greatest nitrogen excretion in fish fed Feed III (14.88 ± 0.08%) and least in fish fed Feed V (11.27 ± 0.07%) (Table 5). The crude lipid remained between 1.14 ± 0.04% (Feed II) and 3.20 ± 0.01% (Feed III).

Carcass analysis of the experimental fish showed greatest crude protein in fish fed Feed V (64.09 ± 0.03%) and least in fish fed Feed III (60.23 ± 0.01%) compared to the initial carcass protein of 59.92 ± 0.01%. The crude lipid percentage remained between 19.39 ± 0.01 (Feed III) and 23.97 ± 0.01(Feed V) (Table 6). The alkaline (ALP) and acid (ACP) phosphatase activities in liver, gill and intestine were greatest in case of fish fed Feed V (59.92 ± 0.01 IU, 61.73 ± 0.01 IU and 60.87 ± 0.01 IU respectively) for ALP (Table 7) and (0.374 ± 0.002 IU, 0.581 ± 0.002 IU and 1.206 ± 0.002 IU respectively) for ACP (Table 8). The greatest concentration of RNA (3788.33 ± 3.06 lg/g) was recorded in the muscle tissue of fish fed Feed V while the corresponding DNA content was the least (114.00 ± 0.00 lg/g). The greatest RNA: DNAratio (33.23 ± 0.03) was registered in the muscle tissue of fish fed Feed V and least (29.42 ± 0.02) in the fish fed Feed III (Table 9). From the above observations, it was noticed that a feed with animal protein level higher than 40% exhibited better daily net weight gain, weight gain percentage and specific growth rate in goldfish, particularly during its growth phase.In the present study, the observations on the specific growth rate (SGR) in relation to dietary protein intake were similar to the findings of Tacon and Cowey (1985). In red tilapia (De Silva et al., 1991) and chinook

salmon (Silver et al., 1991), growth rate or net weight gain was correlated to dietary protein consumption irrespective of dietary lipid content. In the present study, the crude lipid contents of different feeds were dependent upon the quality of ingredients used. The higher fish meal inclusion (40%) in diet resulted in higher crude protein (42.53%) and lipid (7.91%), i.e., in Feed V, attributable to the contents of lipid of 9.80% and crude protein of 52.86% in the fish meal. In addition to the above dietary lipids, vegetable oil and cod liver oil (1:1 ratio) also improved dietary lipid level and subsequently growth and dietary utilisation in feed III treatment, which well justifies similar findings in Cyprinus carpio diet by Watanabe et al. (1977). Yanong (1999) reported 5–7% of optimal lipid requirement in case of older cyprinids compared to 9% during early life stages.

A superior growth performance was noted in fish fed Feed I when compared to fish fed Feed III in spite of the lower protein content present in the former. This observation draws attention to two essential inferences, one, the crude protein present in feed III might be having higher content of indigestible protein and, two, the lower crude lipid content percentage in Feed III (6.63%) might have played a crucial role in feed utilisation patterns. The first inference describes the feed utilisation and growth performance in case of Feed II as well. Ako (1999) reported a crude fat level in commercial ornamental fish feeds at 2–7%. A lipid level of 6.09% in Feed II, therefore, may not have interfered with the feed performance of Feed III. Hence, a poor feed performance of Feed III could be attributed to the protein quality. This is further substantiated by the observation of higher nitrogen excretion in the case of fish fed Feed III. The second inference refers to the phenomenon better known among nutritionists as protein sparing effect . The same also fits the observed growth patterns between Feeds I and V.

The net weight gain, average daily growth and weight gain percentage showed significantly greater values (p 6 0.05) in goldfish fed proteinaceous Feed V. FCR and PER are known to decrease with increasing dietary protein contents (Steffens, 1981; Jauncey, 1982) and the effects vary with species (Dabrowski, 1977). In the present study, similar observation to these values was made. Tabachek (1986) obtained a decrease in PER when he increased dietary protein level at a constant level of dietary lipid. The influence of dietary protein and lipid levels on FCR, PER and PRE has been well justified by De Silva et al. (1991). They concluded that, by increasing dietary lipid levels, protein retention efficiency was increased, thus enhancing the proportion of dietary protein utilised for growth rather than as an energy source. The higher the dietary utilisation, the higher was the P/E ratio as also reported by Mohanty et al. (1996). Therefore, optimum level of P/E ratio becomes an important consideration in diet formulation as energy spares protein for growth when adequately supplied in the diet (Mohanty et al., 1990). Though adult goldfish prefer to eat vegetable matter, the young ones may require a greater amount of protein in their diet for optimum growth. The inclusion of fish meal in the diet of young goldfish, with a maximum digestibility of 93%, could promote their growth of young goldfish (Degani et al., 1997). As is discussed earlier fish meal, being an animal source, would contain high amount of essential amino acid such as lysine which is reportedly a growth promoter in goldfish (Gatlin, 1987), especially during its growth stage. Lysine is reportedly deficient in some plant stuffs (Lovell, 1998).

Goldfish whole-body lysine content analysed by Gatlin (1987) was found to be 8.6% of whole body tissue and the lysine requirement value (Amino acid/Energy ratio) was calculated to be 169, greater than the value of 160 reported in common carp. This reveals that goldfish must require high lysine content feed for optimum diet utilisation and growth. Feed V containing more than 40% fishmeal in turn could have contained similarly high amount of lysine, which might have facilitated better digestion and growth performances. A higher protein turnover and active metabolisation have been further observed on addition of cod liver oil and vegetable oil (Bazaz and Keshavanath, 1993) due to protein sparing effect.Greater carcass composition as observed in Feed V is attributable to high mineral contents in fish meal. Greater percentage of calcium and phosphorus might have facilitated better utilisation of Feed V compared to other feeds. During the course of faecal egestion (specifically when the fish is in its growth stage), fish fed Feed V egested lower nitrogen differing with the observation in Indian major carp rohu (Swain et al., 1996). This indicates that goldfish assimilate more protein in its body and thus egest less nitrogen. In commercial feed however, there was comparatively high nitrogen excretion, the protein not being assimilated in the body for reasons discussed earlier in this section. Similarly, higher lipid was excreted in fish fed commercial diet (Feed III), which could have also contributed to the overall low feed utilisation level. The acid phosphatase activities of liver, gill and intestine also showed an excellent trend and were dependent upon the protein content in the feed. It was observed that in high protein containing feed V, higher enzymatic activity was a good indicator of increased growth and feed conversion. It appears that the greater the protein content in the feed the greater is the activity of acid phosphatase, thereby making this fish more suitable to accept all kinds of feed, and better digestion. The alkaline phosphatase level showed a similar trend initially. This phenomenon was noticed as the experimental fish were in growth phase when it would require a higher level of energy dedicated towards the basic body metabolism. RNA, DNA quantification and their ratio are known to provide dependable indication of growth trend (Sable, 1974; Buckley, 1980; Mustafa and Mittal, 1982; Khan and Jafri, 1991). The ratio was greatest in the fish fed Feed V with high protein and lipid levels that resulted in higher dietary utilisation and best growth. Bazaz and Keshavanath (1993) found higher RNA: DNA ratio in better growing fish fed with oil-supplemented diets with equal level (30–39%) of crude protein. The present study also reports such a finding where, protein and lipid-rich Feed V exhibited better growth as also better RNA:DNA ratio. It was important to notice that while DNA content remained fairly constant, the RNA levels varied significantly which might have occurred due to higher protein utilisation and amino acid and protein synthesis. The commercial feed seem to lack popularisation owing to its higher retail price (Rs 250 or about 5 $US per kg, compared to less than 0.50 $US for formulated diets sans the labour, processing, packaging and marketing cost) and not catering to all the nutritional requirements of the target species as pointed out earlier. Hence, in this perspective, the study reflects its importance for the rural farming community engaged in breeding, culture and marketing of ornamental fish in general and goldfish in particular. Such formulated feeds as used in this present study were all sinking type which necessarily does not interfere with the feeding habit of goldfish, and also does not deteriorate the water quality due to its appreciable water stability (Swain et al., in preparation). The view holds as well for popularisation of these low-cost feeds for aquarists.

3. Conclusions

The conclusions drawn from the present study on growth and dietary utilisation of goldfish (Carassius auratus) are, the growth study revealed that during the growth phase of goldfish (Carassius auratus), feed V with 42.53% animal protein (fish meal) exhibited better daily net weight gain, weight gain percentage and specific growth rate compared to other formulated feeds.The dietary utilisation study in terms of FCR, PRE and ERE showed better performance in feed V (with 42.53% protein) than other feed treatments. Lower protein-containing Feed I exhibited better feed utilisation and growth than in Feed III attributable to higher lipid content. Similarly, Feed II with a lower protein as well as lipid content than Feed III also showed a relatively better growth and dietary utilisation pattern. The commercial feed (Feed III) showed the least utilisation due to poor quality-protein as also lipid contents. The acid and alkaline phosphatase activities were directly proportional to dietary utilisation, being greatest in Feed V compared to other feeds. The RNA:DNA ratio proved to be a good indicator for growth study, and was found to be greatest in case of Feed V. Keeping in view the conclusions drawn from the present study in order to use a better performing, cost-effective protein-lipid rich formulated diet, it is suggested that particularly for growing goldfish young ones, animal protein-based formulated diet with protein content of 40–45% (42.53%, to be exact) using locally available ingredients could be recommended for better growth and dietary utilisation.

Acknowledgment

The authors are thankful to Dr S. Ayyappan, the then Director, CIFA and presently Deputy Director General (Fishery), ICAR, New Delhi, for kindly granting permission to carryout the research work in CIFA, Kausalyaganga, Bhubaneswar. Acknowledgements are also due to Dr P.K. Meher, Scientist, CIFA for his support in statistical analyses.