Fish Feed Pellets Research Articles

Enrichment of commercial feed with new formula products on the growth, yield, and mortality of the giant gourami Osphronemus goramy

Background and objective: The giant gurami (Osphronemus goramy) is considered the most desirable freshwater species in Indonesia, mainly for food security. This study evaluated the effectiveness of newly formulated products containing water, coconut, palm sap sugar, and fungus used for enriched commercial feed and their impact on gurami sago’s (local strain) growth performance, yield, and mortality. Methods: A total of 100 g of palm sugar are cooked with 1,000 ml of freshwater for fifteen minutes at a temperature of 60 °C. Furthermore was added 2,000 ml of mature coconut water. For every 1,000 ml of a mixture of mature coconut water and palm sap sugar solution was added 2 g of Aspergillus niger (called product P1), 2 g of Rhizopus oligosporus (product P2), and 2 g of Saccharomyces cerevisiae (product P3). Commercial fish feed pellets enriched with P1, P2, and P3 were designated as P1, P2, and P3 diets. At the same time, the commercial feed added with freshwater is called P4 feed (placebo). The dosage of each product is 300 ml/kg of feed. Juvenile sago gourami (initial weight 50±2.5 g and total length 13.2±0.4 cm) were stocked in triplicate (0.5x0.5x0.5 m) in a freshwater concrete pond with a stocking density of 30 individuals. /net, an initial feeding rate of 3% per day for 90 days of the experiment. Results: The weight gain ranged from 172.43 to 215.6%, the specific growth rate increased from 0.60 and 0.75%/day. The coefficient of thermal growth increased from 27.26 to 32.83. At the same time, yield ranging from 14.88 to 21.03 g/L and mortality for 90 days of the experiment decreased from 22.22% to 6.66%. The coefficient of variation in weight was between 0.68% and 1.30%. Conclusion: Giant gourami juvenile survived and grew well in diet P2, moderate growth in diet P3, and diet P1; the lowest growth was recorded in diet P4.

Physical properties and dietary effects of Abelmoschus esculentus leaves used as binders in fish feed

Abstract. The experiment was conducted to assess the use of Abelmoschus esculentus leaves powder as binders in the production of fish feed pellets. Six experimental diets were formulated with three containing starch as binder while the other three contained A. esculentus as binder. Each diet contained maize or wheat individually or in combination as energy source. The diets were designated as MAI (Maize only), WHE (Wheat only), MAW (Maize and Wheat only), MAA (Maize and A. esculentus), WHA (Wheat and A. esculentus) and MWA (Maize, Wheat and Abelmoscus esculentus). Physical properties and dietary effects of the diets were assessed using Oreochromis niloticus fingerlings. There was significant difference (P<0.05) in the sinking rate (cm.sec-1), thickness strength (mm), water absorption index, hardness (mm) and water stability (%) and bulk density (g.cm-3) of experimental diets. Diet MAI (Maize only with corn starch) had a significantly slower sinking rate of 6.77±0.10 cm.sec-1 when compared to the other diets. Diets MAA (Maize only with A. esculentus) and MAW (Maize and Wheat with corn starch) had the highest water stability (88.90±0.46%) while the lowest was diet MAI (85.20±0.10%). Crushing load value for the diet MWA (Maize and wheat with A. esculentus) of 357.00±0.00N was the highest and 119.00±0.00 N for diet MAI was the least. There was significant difference (P<0.05) in the friability of experimental diets at different revolution speed. There were no significant differences (P>0.05) in the mean final weight, mean weight gain, specific growth rate, feed conversion ratio, and feed efficiency of experimental fish fed with the experimental diets. Fish fed diet MAA had a significantly higher (P<0.05) mean weight gain, specific growth rate, feed efficiency ratio compared to the fish fed other diets. The results from this experiment showed that A. esculentus leaf soaked for 24 hours can be used as binder in fish feed production.

Effects of Formulation on the Palatability and Efficacy of In-Feed Praziquantel Medications for Marine Finfish Aquaculture.

Praziquantel (PZQ) provides an effective treatment against monogenean parasitic infestations in finfish. However, its use as an in-feed treatment is challenging due to palatability issues. In this study, five formulations of PZQ beads (1–4 mm) were developed using marine-based polymers, with allicin added as a flavouring agent. All formulations attained PZQ loading rates ≥74% w/w, and the beads were successfully incorporated into fish feed pellets at an active dietary inclusion level of 10 g/kg. When tested for palatability and digestibility in small yellowtail kingfish, the PZQ-loaded beads produced with alginate-chitosan, alginate-Cremophor® RH40, and agar as carriers resulted in high consumption rates of 99–100% with no digesta or evidence of beads in the gastrointestinal tract (GIT) of fish fed with diets containing either formulation. Two formulations produced using chitosan-based carriers resulted in lower consumption rates of 68–75%, with undigested and partly digested beads found in the fish GIT 3 h post feeding. The PZQ-loaded alginate-chitosan and agar beads also showed good palatability in large (≥2 kg) yellowtail kingfish infected with gill parasites and were efficacious in removing the parasites from the fish, achieving >90% reduction in mean abundance relative to control fish (p < 0.001). The two effective formulations were stable upon storage at ambient temperature for up to 18 months, showing residual drug content >90% compared with baseline levels. Overall, the palatability, efficacy and stability data collected from this study suggest that these two PZQ particulate formulations have potential applications as in-feed anti-parasitic medications for the yellowtail kingfish farming industry.

Variations in Microbial Community on the Nutrient Content of Fermented Fish Feed Pellets with Tofu Waste

Tofu industrial waste has the potential to become an environmental pollutant when not treated optimally, so it needs proper treatment to minimize pollution. Fish farmers are expected to be able to innovate in terms of fish cultivation, so that harvest yields can be optimal to meet food needs. Furthermore, fermentation technology by Saccharomyces cerevisiae and Rhyzopus oligosporus are potential fungi that can increase the nutritional value of waste. This research aimed to produce an appropriate technology to produce fish feed pellets from fermented Saccharomyces cerevisiae and Rhyzopus oligosporus based on waste. This research method was designed in the form of research using a completely randomized design with 4 treatments (P0 without microbes); (P1 given Saccharomyces cerevisiae (2 gr) and Rhyzopus oligosporus (2 gr); (P2 Saccharomyces cerevisiae (1 gr) and Rhyzopus oligosporus (3 gr); (P3 Saccharomyces cerevisiae (3 gr) and Rhyzopus oligosporus (1 gr) with 3 replication. The research results showed that: there was an effect of variation in microbial community on the nutrient content of the Fermented Fish Feed Pellets with Tofu Waste. Treatment P1 gave the highest protein and β -glucan content. Production of fermented fish feed pellets waste-based feed for catfish is the implementation of waste product, which can be further developed to meet the quality of the feed produced.

Nutritional and microbial quality of extruded fish feeds containing black soldier fly (Hermetia illucens L) larvae meal as a replacement for fish meal for Nile Tilapia (Oreochromis niloticus) and African sharptooth catfish (Clarius gariepinus)

ABSTRACT The black soldier fly (Hermetia illucens L.) is a potential substitute of fish meal in feeds. However, information on the nutrition and safety of these feeds is inadequate. This study examined the quality of fish feed pellets extruded from blends formulated with and without black soldier fly larval meal (BSFLM). A further aim was to study the influence of extrusion processing types on feed composition. Two iso-proteinous feed blends containing 28% protein were formulated with 0% BSFLM (BSFLM0) and 75% BSFLM (BSFLM75). The feed blends were then cold- or hot-extruded (CE or HE) and the products analyzed for proximate composition, amino acids, fatty acid profiles and microbial content. The BSFLM75_HE pellets contained significantly higher levels of fat (15.6%), leucine (11.5 mg/g), and oleic acid (79.1 µg/g). Hot extrusion concentrated phenylalanine and leucine, increased polyunsaturated fatty acids and saturated fatty acids and decreased total viable counts, coliforms, yeast and molds, endospores and Salmonella.

Nutritional Performance of Juvenile Red Drum (Sciaenops ocellatus) Fed Various Fish, Shrimp, and Squid Diets

Aquaculture is the fastest-growing sector of protein production in the world. Due to the rising costs of fishmeal used as a critical ingredient to make pelleted fish feed, the industry is moving to replace fishmeal as a primary protein source without reducing the growth rate of aquacultured fish. A 12-week feeding trial utilizing juvenile red drum (Sciaenops ocellatus) was conducted to determine the performance of various combinations of natural diet components including fish (Decapterus punctatus), shrimp (Litopenaeus vannamei), and squid (Loligo opalescens and Illex), in addition to a commercial fishmeal-based pelleted feed, fed isocalorically to identify if there is an optimal combination for red drum growth and health. These results can provide information to develop fishmeal replacement diets (FMRDs) that can more closely mimic the performance of natural diets. Traditional aquaculture metrics showed that fish fed the diet comprised only of fish had the highest specific growth rate, condition factor, and protein conversion efficiency, with the lowest feed conversion ratio, indicating the fish component was the highest performing component for red drum growth on a calorically fixed ration. There were significant differences among eight groups found for traditional aquaculture metrics ( p &lt; 0.05 ). The commercial pelleted feed performed better than all but the fish only natural diet treatments in terms of growth on a fixed ration, which indicated that it is nutritionally balanced. The results of this study show that there were performance differences between juvenile red drum fed various natural diets. There has been an investigation into the metabolome of these fish to identify potential metabolites for supplementation into FMRDs, which is not addressed in this paper.

PEMANFAATAN SAMPAH SAYURAN RUMAH TANGGA MENJADI PELET PAKAN IKAN LELE (CLARIAS GARIEPINUS)

Vegetable waste that is not utilized causes an unpleasant odor effect and disturbs the aesthetics of the environment, wet waste thrown away can become a breeding ground for insects. One of the waste utilization methods is the manufacture of fish pellets. The purpose of this study is to utilize household vegetable waste used for fish feed pellets. The research design used was a pre-experimental design with a posttest only research design. The object of this research is vegetable waste originating from household activities. The treatments used were 3 variations of vegetables (20%, 30%, 40%) repetition which was carried out 3 times with a concentration of 1 kg. Making fish pellets using a machine that has been modified as a supporting tool for making pellets. The pellets produced were subjected to laboratory tests to determine the water content, ash content, fat content, crude fiber content, protein content referring to SNI (01-4087-2006) concerning catfish feed regulations. The results showed that from variation 1 (20%), variation 2 (30%) and variation 3 (40%) none of them met the Indonesian National Standard with water content, ash content, fat content, and protein content. crude fiber still does not meet because it is still under the provisions of SNI. It was concluded that there were no pellets made from vegetable waste that met the stipulation value of SNI. The percentage that can be reviewed for the formulation is that the percentage of shrimp head flour can be increased to 20% and the fine bran can be reduced to 40%. For the community, it can be useful to overcome the problem of vegetable waste being dumped directly into the surrounding environment without any processing of the vegetable waste to be used as fish feed pellets.

Morphoanatomy of Pangasionodon hypopthalmus Reared Under Controlled Photoperiod

Fish morphoanatomy is affected by environmental condition such as photoperiod duration. A research on the effects of shortened photoperiod on the morphoanatomy of Pangasionodon hypopthalmus has been conducted. There were 3 treatments applied, namely, 24 hours dark (24D), 18 hours dark (18D) and natural photoperiod (control). The fish, 8 cm total length (TL) and 4 gr body weight (BW) were reared in circular plastic tanks filled with 100 L freshwater and completed with aerators and circulation pumps, 30 fishes/tank. The fish was reared for 8 weeks and fed with commercial fish feed pellets, twice/day, at satiation. The dark condition was created by placing the tanks under dark tarp tents. Morphoanatomy data were studied by the end of experiment. Results shown that the survival of fish was 100%. The growth of fish reared in 24D and 18D was better, more than 20 cm TL and 85 gr BW, while that of the control was 18 cm TL and 72 gr BW. The condition factor as well as the liver condition of fish in all treatment was not different, it was around 1.2. The liver was reddish brown color, smooth and oily in which hepatosomatic index (HSI) value 0.023 in 24D; 0.027 in 18D and 0.048 in control. The visceralsonatic index (VSI) was 0.090 in 24D; 0.70 in 18D and 0.161 in control. In most of fishes reared in 24D and 18D, the gonad were in the 1st maturity stage (gonadosomatic index; GSI 0.0058 to 0.0068), while the gonad of some control fishes were in the 2nd maturity stage (GSI 0.0080). Data obtained shown that the morphoanatomical data (HSI, VSI and GSI) of the fish reared in lengthened dark were lower, but the growth data (TL and BW) was higher than those of the control, indicated that the fish reared in dark condition may allocated more energy for growing.

Sustainability Analysis of Fish Feed Derived from Aquatic Plant and Insect

Fish and meat production and processing will grow drastically in the coming decades. In aquacultural systems, insects are gaining interest as feed to provide a sustainable alternative to the fishmeal paradox, whose production leads to high consumption of resources and negative environmental impacts. Within the scope of this study, the production of fish feed from Hermetia illucens larvae and Lemna minor in an inline recirculating aquaponics model for urban sites was developed and optimized, which efficiently combines waste and environmental service concepts in one production system. At the same time, the value chain produces high-quality, market-accessible raw materials for the fish feed industry. All investigations were accompanied by a comparative Life Cycle Assessment (LCA) to measure and compare ecological effects to finally result in sustainable alternatives. The results achieved in this research show that fish feed based on Hermetia illucens and Lemna minor can have the potential to be ecologically competitive or more sustainable than standard feed. It should be noted that the comparison here represents the results of the project on a pilot scale. Various optimization potentials were shown, which are essential for the large-scale implementation of the breeding of both species as well as their processing up to the fish feed pellets.

COMPARISON OF GROWTH RATE OF THREE CATFISH (Pangasius Hypopthalmus) WITH DIFFERENT KINDS OF FEED

&lt;p&gt;Feed is one factor that can support the development of fish farming is intensive and semi-intensive, both freshwater fish, brackish water fish, and sea water fish. While the feed required by the fish since the start of the size of the larvae (fry), up to the size of the parent. However, the feeding of the fish also can be creation to maximize growth. Fish growth is strongly influenced by the quality of the feed and therefore the need to do research, causes of a different kind of feed to seed the growth hormone of catfish. Here the research I did was observe the ratio of the growth rate of catfish that I give a different feed types among which the pellets, the remains of fish and leaves. The research of method used in this study is a quantitative method that is located in the home. And the observation time that I did was for 9 weeks. It turned out that the results shown by the fastest growth in the given fish feed pellets.&lt;/p&gt;

Improvement of the composition value of commercial fish feeds with additional waste of torpedo scad fish scales, water hyacinth, and taro leaves

Waste material has a lot of nutrients needed so that it can reduce the price of fish feed. Waste that can be used includes the scales of Torpedo Scad fish (Megalapsis cordyla), taro leaves (Colocasia esculenta), and water hyacinth (Eichornia crassipes). This research was conducted to obtain the correct composition of the three wastes in influencing the physical properties and composition values of commercial fish feed. Composition values tested include levels of protein, fat, carbohydrates, ash content, and water content. This research method begins by refining the commercial pellets, fish scales of Torpedo Scad, taro leaves, and water hyacinth then filtering them with a 125 mesh sieve. After that, mix the ingredients in the ratio A1 A2 and A3. After that, test the composition value of each comparison. The results of this study indicated that the addition of Torpedo Scad fish scales, taro leaves, and water hyacinth were significantly different (P <0.05) on protein and carbohydrate content and fish feed pellets that had been made. It can be excluded that the addition of the waste scales of Torpedo Scad fish, taro leaves, and water hyacinth has an influence on the composition of protein and carbohydrates from fish pellets.

Identification and Prevalence of Fungi on African Catfish (Clarias gariepinus) Fed with Pellets from Smoked Fish Waste

Smoked fish processing waste has a high nutritional content that can be used as a raw material for fish feed (pellets). One standard of fish pellets based on BSN is there must be no aflatoxin content produced from Aspergilus flavus. Qualitative analysis of aflatoxin content can be seen from the presence or absence of A. flavus fungi. In this study the identification of fungi on pellets, fish, and water for maintenance is discussed. Pellets made from smoked fish processing waste are grouped into: K.0 (control), K.1 (100% raw material + 0% fish feed), K.2 (70% raw material + 30% fish feed), K.3 ( 40% raw material + 60% fish feed), and K.4 (10% raw material + 90% fish feed). Pellets were given to African catfish for 30 days of maintenance. The identification of fungi was carried out on pellets, African catfish, and pond water. The identification results in three fungi namely Rhizopus oryzae, Aspergilus niger, and Fusarium oxysporum.

Growth and health status of Pangasionodon hypophthalmus reared under manipulated photoperiod conditions

Background: In general, the length of photoperiod affects the physiology of Pangasionodon hypophthalmus. This study aimed to understand the growth and health status of this fish reared under manipulated photoperiods. Methods: The study was conducted between June to August 2020[A1] . Three treatments were applied: control (natural photoperiod); 18 hours of darkness (18D6L; tanks were placed under a dark tarp tent for 18 hours); and 24 hours of darkness (24D0L; tanks were placed under a dark tarp tent continuously). Three replications were performed per treatment. At baseline, fish were approx. 7.5 cm [A2] total length (TL) and 4 g body weight (BW), and were reared in circular plastic tanks (100 L; 30 fish/tank) with aerators and filters, and fed with commercial fish feed pellet (2 times/day to satiation). Fish growth and survival were studied once/week, and blood and tissue samples were taken at the end of the experiment (8 th week). Tissue was formalin fixed and HE stained. Results: The survival of fish in all treatment was 100%. The fish reared in 24D0L and 18D6L grew better than control, achieving mean TL of 23 cm and BW of 98 g (control = 19 cm TL and 72 g BW). There was no difference in hematology condition or tissue structure between the three groups. Tissue structure of gill, kidney and liver were normal, but light abnormality due to parasites was present in the gill of fish reared in 24D0L. Blood samples for all three groups showed mean red blood cell count of 1,800,000 cells/ml and white blood cell (WBC) count of 55,200 cells/ml. WBC consisted of lymphocyte 65%, monocyte 24%, thrombocyte 6%, neutrophil 3%, eosinophil 1% and basophile 1%. Conclusion: Data obtained indicate that a short photoperiod improves the growth of P. hypophthalmus fish and does not negatively affects their health.

PERFORMANCE EVALUATION OF A NOVEL DESIGN OF FEED PELLETS VERTICAL COOLER

This work aims to report a novel design of feed pellets vertical cooler named as double bed vertical cooler (DBVC). The proposed DBVC is assessed experimentally using sinking fish feed pellets produced by a ring-die pelletizer under different operating parameters including the position air double vacuum fans, height of the feed pellets as a function of pellet retention time inside the cooler and different widths of sieve slit. The performance evaluation of DBVC was performed and compared to performance of the single bed vertical pellet cooler (SBVC) that used commercially in the feed pellets industry in Egypt. The comparison was carried out at constant cooler’s capacity of 2 Mg/h for both coolers in terms of the performance indicators such as; output pellets temperature and moisture content, cooling efficiency, pellet durability, required specific energy.. etc. Moreover, the two types of coolers have been analyzed from the economic point of view using the life cycle cost (LCC) method. Under the best operating conditions for both cooler, the obtained results showed that the temperature and moisture content for the outlet pellets were reduced by about 5.55% and 10.60%, respectively by using DBVC. Using DBVC gave slight increase in cooling efficiency and pellet durability by about 3.35% and 4.60%, respectively over SBVC with an explicit reduction in the required cooling energy by about 30.83%. From the economic aspect, the total capital cost and total cooling cost per unit of production for DBVC are lower than SBVC by 73.91% ( the price difference between them saving 4885.87$) and 61.26% ( saving 0.77 $/Mg), respectively. Ultimately, it is clear that the DBVC proved a high performance and saved the costs of feed pellet cooling process

Growth Performance and Survival in the Crayfish (Astacus astacus) Fed Fish Faeces, Combined Plant Root/Fish Faeces and a Commercial Pelleted Fish Feed

Growth Performance and Survival in the Crayfish (Astacus astacus) Fed Fish Faeces, Combined Plant Root/Fish Faeces and a Commercial Pelleted Fish Feed

Growth and health status of Pangasionodon hypophthalmus reared under manipulated photoperiod conditions

Background: In general, the length of photoperiod affects the physiology of Pangasionodon hypophthalmus. This study aimed to understand the growth and health status of this fish reared under manipulated photoperiods. Methods: The study was conducted between June to August 2020[A1] . Three treatments were applied: control (natural photoperiod); 18 hours of darkness (18D6L; tanks were placed under a dark tarp tent for 18 hours); and 24 hours of darkness (24D0L; tanks were placed under a dark tarp tent continuously). Three replications were performed per treatment. At baseline, fish were approx. 7.5 cm [A2] total length (TL) and 4 g body weight (BW), and were reared in circular plastic tanks (100 L; 30 fish/tank) with aerators and filters, and fed with commercial fish feed pellet (2 times/day to satiation). Fish growth and survival were studied once/week, and blood and tissue samples were taken at the end of the experiment (8 th week). Tissue was formalin fixed and HE stained. Results: The survival of fish in all treatment was 100%. The fish reared in 24D0L and 18D6L grew better than control, achieving mean TL of 23 cm and BW of 98 g (control = 19 cm TL and 72 g BW). There was no difference in hematology condition or tissue structure between the three groups. Tissue structure of gill, kidney and liver were normal, but light abnormality due to parasites was present in the gill of fish reared in 24D0L. Blood samples for all three groups showed mean red blood cell count of 1,800,000 cells/ml and white blood cell (WBC) count of 55,200 cells/ml. WBC consisted of lymphocyte 65%, monocyte 24%, thrombocyte 6%, neutrophil 3%, eosinophil 1% and basophile 1%. Conclusion: Data obtained indicate that a short photoperiod improves the growth of P. hypophthalmus fish and does not negatively affects their health.

Physico-chemical characteristics of Rhizopus sp.-fermented fish feed pellets containing black soldier fly larvae (Hermetia illucens) meal

In aquaculture, feed cost contributes the highest share in the total production cost. The increase in fishmeal price and the high cost of commercial fish feeds have prompted the search for alternatives. Thus, considerable research has been carried out to develop a farm-made feed that requires simpler methods and cheaper production costs. This study aimed at developing farm-made fish feed using simple equipment, locally available materials, and inexpensive fungal-based bio-floating technique. A combination of using black soldier fly (Hermetia illucens) larvae meal as a fishmeal replacement and Rhizopus sp. fermentation to provide floatability was used. An experiment using three different Rhizopus sp. inoculum doses (1, 2, and 3% w/w) and 3 different fermentation duration (30, 40, and 50 h) were designed, with unfermented feed as control. Results showed that fermented floating feeds gained better nutritional value and physical characteristics (p<0.05). The optimized treatment resulted in a fermented feed with the protein content of 29.72%; fibre 12.13%; fat 26.57%; and ash 7.83%. Relative to the unfermented control, all of the fermentation treatments produced feeds with high average values of floating ability (83.33%) and water stability (92.38).

Hematology of Pangasionodon hypopthalmus Reared Under Controlled Photoperiod

Manipulated photoperiod has been used to improve the growth of cultured Pangasionodon hypopthalmus. Photoperiod length affects the fish physiology in general and thus reflected in its hematological condition. The hematology of P. hypopthalmus reared in short photoperiod was studied in May–August 2020. There were three treatments applied, namely natural photoperiod (P-Nat, fish tanks were placed under clear plastic tent), 18 hours dark (P-18D, the tanks were placed under dark tarp tent for 18 hours) and 24 hours dark (P-24D, the tanks were placed under dark tarp tent continuously). The fish (3 inches TL, 4 grams BW) were reared in circular tanks ( 100 L) at a density of 30 fishes/tank and fed with commercial fish feed pellets twice a day,, ad libitum. Blood samples were obtained prior to the experiment and at the 8th week. Results showed no significant differences in hematological parameters of the fishes among treatments. The number of erythrocytes and leucocytes in the pre-treated fish was approximately 1,850,000 and 55,200 cells/ml, respectively. While those of the treated fish was 1,760,000 and 54,600 cells/ml (P-Nat); 1.760.000 and 55,000 cells/ml (P-18D) and 1,790,000 and 55,000 cells/ml (P-24D). In pre-treated fish as well as all treated fishes, hemoglobin was around 10 g/dL and glucose was around 110 mg/dL. The percentage of leucocyte type cells were as follows: lymphocyte 65%, monocyte 24%, thrombocyte 6%, neutrophil 3%, eosinophil 1% and basophile 1%. The value of hematological parameters indicate that the fish was in normal and healthy condition and thus it is proved that shortened photoperiod do not affects P. hypopthalmus health in general.

Growth and health status of Pangasionodon hypophthalmus reared under manipulated photoperiod conditions.

Background: In general, the length of photoperiod affects the physiology of Pangasionodon hypophthalmus. This study aimed to understand the growth and health status of this fish reared under manipulated photoperiods. Methods: The study was conducted between May and August 2020. Three treatments were applied: control (natural photoperiod); 18 hours of darkness (18D6L; tanks were placed under a dark tarp tent for 18 hours); and 24 hours of darkness (24D0L; tanks were placed under a dark tarp tent continuously). Three replications were performed per treatment. At baseline, fish were approx. 3 inch total length (TL) and 4 g body weight (BW), and were reared in circular plastic tanks (100 L; 30 fish/tank) with aerators and filters, and fed with commercial fish feed pellet (2 times/day to satiation). Fish growth and survival were studied once/week, and blood and tissue samples were taken at the end of the experiment (8 th week). Tissue was formalin fixed and HE stained. Results: The survival of fish in all treatment was 100%. The fish reared in 24D0L and 18D6L grew better than control, achieving a mean TL of 23 cm and BW of 98 g (control = 19 cm TL and 72 g BW). There was no difference in hematology condition or tissue structure between the three groups. Tissue structure of gill, kidney and liver were normal, but light abnormality due to parasites was present in the gill of fish reared in 24D0L. Blood samples for all three groups showed mean red blood cell count of 1,800,000 cells/ml and white blood cell (WBC) count of 55,200 cells/ml. WBC consisted of lymphocyte 65%, monocyte 24%, thrombocyte 6%, neutrophil 3%, eosinophil 1% and basophile 1%. Conclusion: Data obtained indicate that a short photoperiod improves the growth of P. hypophthalmus fish and does not negatively affects their health.

Preparation of feed with metal oxide nanoparticles for nanomaterial dietary exposure to fish and use in OECD TG 305

The first step of nanomaterial accumulation in the aquatic environment is the uptake of particulate material. For substances with very low water solubility, exposure via water may be of limited relevance in comparison to the dietary route. The OECD Test Guideline 305 for bioaccumulation testing in fish using dietary exposure recommends to add substances to fish food following methodologies normally used in aquaculture (e.g. with a corn or fish oil vehicle). The feasibility of using such an approach for the testing of manufactured nanomaterials (MNs), due to their unique physical characteristics and solubility, needs to be investigated. In this study an easy, cost-effective method to prepare metal oxide nanoparticle (NP) spiked feed to give the required dietary exposure concentration to fish is described. Metal oxide NP (CeO2,TiO2 and ZnO) dispersions were prepared in oil (sunflower or olive oil) and used to soak fish feed pellets. NP surface deposition and homogeneity of distribution were analysed and confirmed. Discrepancies between nominal and measured concentrations highlighted the need to measure the achieved concentration in MN-spiked feed. The present method provides stable concentrations for bioaccumulation testing of MNs in fish through the dietary route.A method for•Fish feed preparation using nanomaterial-oil suspensions.•Homogenous spiking of nanomaterials on feed.•Nanomaterials stably maintained on feed immersed in water until eaten by fish.