The chironomid larvae are widely recognized as an important food for many fish and cultured invertebrates, such as crustaceans (Armitage, 1995; Tidwell et al., 1997). This food, used in vivo, in frozen and in dry, is an excellent source of protein, lipid, vitamins and minerals (e.g., Czeczuga & Gierasimow, 1973; De La Noűe & Choubert, 1985; Habib et al., 1997, Bogut et al., 2007, Kara, 2013). This food is characterized by the relatively high protein content (up to 56%), the high digestibility (De La Noűe & Choubert, 1985) and the high energy content.

Crude protein, fat, water, ash, dry matter, essential amino acids and fatty acids are analyzed from freshly collected Chironomus plumosus larvae in order to evaluate their suitability as the components for farmed fish diet (Bogut et al., 2007). Crude protein content are 7,6 % and 55,7 % in fresh larvae and dry matter, respectively, being adequate for growth needs of all freshwater fish sorts and categories. Phenylalanine (2,76 % of dry weight), leucine (2,49 %) and lysine (2,48 %) are most abandant among essential amino acids. In sum, essential amino acids in C. plumosus larvae are present in quantities adequate for feeding majority of omnivorous and carnivorous freshwater fish species (Bogut et al., 2007).

The content of free amino acids in larvae of C. annularius is studied by Czeczuga & Gierasimow (1973). Aspartic acid is found in the largest amounts, 6,17 g % of dry mass, the next are such amino acids as glutamic acid (5,04 g %), leucine together with isoleucine (4,86 %) and alanine (4,58 g %). Habib et al. (1997) have studied 14 species of chironomid larvae, with the dominance of Chironomus javanus, grown in algal culture, Chlorella vulgaris. Glutamic acid (9,44 % of total acids), aspartic acid, glycine and alanine are most abundant than other amino acids.

In C. plumosus, crude fat content are 1,3 % and 9,7 % in fresh larvae and dry matter, respectively, being energetically sufficient for all warm water living fish (Bogut et al., 2007).  The crude fat contains 26,12 % saturated, 30,42 % monounsaturated and 34.03 % polyunsaturated fatty acids. In general, chironomid larvae contain more amounts of unsaturated fatty acids (Habib et al., 1997) that is needed for normal growth of freshwater fish and prawn fry.

Basic References

Armitage P.D. 1995. Chironomidae as food. The Chironomidae: biology and ecology of non-biting midges. Armitage P.D., Cranston P.S., Pinder L.C.V. (Editors.). Chapman and Hall, London, 423-435

Bogut I., Has-Schon E., Adamek Z., Rajković V., Galović D. 2007. Chironomus plumosus larvae as suitable nutrient for freshwater farmed fish. Poljoprivreda 13, 159-162

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Zooplankton

The amino acid content in freshwater copepods (Eudiaptomus zachariasi), cladocerans Daphnia pulex and Ceriodaphnia sp. as well as copepodites (Cyclops strenuus) is studied by Dabrowski & Rusiecki (1983). Yet, the amino acid content in saltwater brine shrimp, Artemia salina, nauplii on hatching and during fasting is determined.

The major free amino acids in C. strenuus dry matter are 1,43 % arginine, 0,22 % histidine, 0,20 % alanine, 0,15 % glutamic acid and 0,11% lysine. Free arginine content decreases in the daphnids as they increase in the size. The content of all free amino acids in fasting Artemia nauplii is lower than in the freshwater zooplankters. The major free amino acids in nauplii are 0.55 % proline, 0.41 % alanine, 0.34 % glycine and 0.37 % serine, respectively.

Chemical composition of Daphnia longispina and other daphnids is studied by Holm & Walther (1988). Non-polar amino acid alanine ((from 13,4 mol % to 20,3 mol %), basic amino acids arginine (11,6 mol %) and lysine (10,2 mol %) as well as polar, uncharged amino acid glycine (10,0 mol %) are most abundant in the plankton extract.

The same authors have demonstrated rapid leakage of amino acids from frozen daphnids upon thawing.

The moisture content, crude protein level and amino acid profile of three freshwater zooplankton (Moina micrura, Diaphanosoma excisum, Brachionus calyciflorus) commonly used for rearing fish larvae are analyzed by Ovie & Ovie (2006). The moisture contents and crude protein levels are similar, as follows: M. micrura 89,0 % and 52,4 %; D. excisum 89,3 % and 57,3 %; B. calyciflorus 91,6 % and 50,3 %, respectively. The samples are represented by 17 amino acids: nine essential and eight non-essential amino acids. The dominant essential amino acids (per 16 g N) in M. micrura are lysine (10.73 g), arginine (8,17 g) and leucine (8,0 g); in D. excisum lysine (9,95 g), leucine (8,0 g) and valine (6,23 g); in B. calyciflorus leucine (8,95 g), lysine (8,64 g) and arginine (6,37 g). According to Ovie & Ovie (2006), in all three species tested (M. micrura, D. excisum, B. calyciflorus), glutamine and aspartic acid dominate the non-essential amino acid profile.

Seasonal Variations

Seasonal variations in the concentrations of 19 free amino acids in the whole body homogenates of freshwater amphipod Gammarus pseudolimnaeus are measured by Graney & Giesy (1986). The greatest total concentrations of free amino acids, 226,9 and 286,4 nmol per mg dry weight, are observed in April and May, with declining through summer months. The pattern of relative concentrations of individual free amino acids in G. pseudolimnaeus is found to be similar to that of other freshwater invertebrates. Alanine represents the most abundant amino acid (16,2-22,4 %) throughout an entire year. Arginine and leucine exhibit the next greatest abundances and comprised an average of 10,2 and 10,4 % of the total free amino acid concentration, respectively.

Holm & Walther (1988) give seasonal variations in the concentrations of free amino acids in D. longispina and other daphnids.

Amino acid profile of amphipod Gammarus lacustris in the beginning of autumn has the high level of alanine (22,6 mmol per ml of homogenate) and ornithine (17,6 mmol) (Karanova & Andreev, 2010). The amount of alanine and ornithine accounts for 39,8 % of the total pool of free amino acids, taken together alanine, ornithine, lysine and leucine form 55% of this pool.

Decapoda

The abdominal muscle, antennal gland, haemolymph, hepatopancreas and ovary of freshwater Astacus leptodactylus are analysed for free and protein-bound amino acids by van Marrewijk & Ravestein (1974). Free amino acid content is highest in the abdominal muscle and lowest in the haemolymph. The most abundant free amino acids are glycine, arginine and alanine. Together they account for up to 38 mol % in the hepatopancreas and up to 73 mol % in the abdominal muscle of the total amount. The content of free amino acids in the hemolymph of three crayfish species, Astacus astacus, A. leptodactylus and Ortonectes limosus, is researched by Rogala et al. (1978), setting the differences in lysine and histidine content.

In freshwater Chinese mitten crab, Eriocheir sinensis, and A. astacus concentration of amino acids is less than in marine decapods (Camien et al., 1951) (mitten crab is an invasive species that lives in freshwater but migrates seawards to breed).

Freshwater molluscs, snails (Gastropoda) and mussels (Bivalvia), are an excellent food for many species of freshwater fish and crustaceans. In rivers, lakes and reservoirs, molluscs form powerful bottom placers and foulings that are actively exploited by many cyprinid and other fish.

For example, it is shown that bream, Abramis brama, white bream, Blicca bjoerkna, common roach, Rutilus rutilus, and carp, Cyprinus carpio, can eat zebra mussel, Dreissena polymorpha, of size ranged from 1-2 to 45 mm depending on fish age (Prejs et al., 1990; Nagelkerke & Sibbing, 1996; Tucker et al., 1996). The real switch to zebra mussels would be expected in fish of 23–24 cm length (Prejs et al., 1990). Other abundant freshwater molluscs are Viviparus viviparus, V. ater, V. contectus and other viviparous snails. For example, newborn V. ater are eaten by barbel, Barbus barbus, roach, R. rutilus, rudd, Scardinius erythrophtalmus and tench, Tinca tinca (Keller & Ribi, 1993), while adult viviparids (with the relatively hard shell and shell size up to 45 mm) are eaten by all large cyprinid fish with the well developed pharyngeal teeth.

Composition

The proximate compositions and fatty acid profiles of the freshwater mussels Unio terminalis and Potamida littoralis are compared by Ersoy & Şereflişan (2010).  The crude protein (11,87-11,97 %), lipid (2,55-1,05 %), ash (1,68–1,61%) and moisture (80,36-81,69 %) contents of U. terminalis and P. littoralis are observed. Lipid content in U. terminalis is found to be significantly higher than in P. littoralis. The percentages of total saturated fatty acids and total monounsaturated fatty acids are higher in U. terminalis than in P. littoralis. At the same time, the corresponding content of total polyunsaturated fatty acids is lower. The n3-n6 ratio are 1,54-1,40 in U. terminalis and P. littoralis, respectively. Using these data, Ersoy & Şereflişan (2010) conclude that freshwater mussels U. terminalis and P. littoralis are suitable as the healthy food.

Freshwater and Saltwater Molluscs

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Free amino acid content in three species of earthworms, cosmopolitan tiger worms, Eisenia foetida, African earthworms, Eudrilus eugeniae, and Indian blue worms, Perionyx excavatus, are studied by Reinecke et al. (1991). Leucine and arginine are most abundant among essential amino acids in all three species. Crude protein content are 66,13 % in E. foetida, 58,38 % in E. eugeniae, 61,63 % in P. excavatus and 61,00 % in fishmeal, for comparison. The amino acid profile in four species of earthworms namely E. eugeniae, Hyperiodrilus africanus, Alma millsoni and Libyodrilus violaceus, in comparison with E. foetida, is studied by Dedeke et al. (2010). Arginine is most abundant in four African species and one of the abundant essential amino acids (after leucine and lysine) in E. foetida. Glutamic and aspartic acids, among non-essential amino acids, are most abundant than arginine and leucine in all five species, achieving 16,4 g per100g crude protein in E. foetida.

Lysine and methionine, that are limited amino acids in most feedstuffs, are present in all species of earthworms (Dedeke et al., 2010).

Earthworm Meal

Earthworm meal (Lumbricus rubellus) has become one of the natural materials that can be used as feed additive. The study of Istiqomah et al. (2009) is carried out (1) to evaluate the amino acid profile of earthworm and earthworm meal, (2) to calculate the value of essential amino acid index of both materials. It is shown that essential amino acid of earthworm is dominated by histidine (0,63 % of dry matter basis), meanwhile the earthworm meal is dominated by isoleucine (1,98 %). The non-essential amino acid of earthworm and earthworm meal is dominated by glutamic acid (1,52 % and 3,60 % of dry matter basis, respectively). The value of essential amino acid index obtained from earthworm meal is higher (58,67,%) than those from earthworm (21,23 %). It is concluded that powdering method of earthworm by using formic acid addition has higher amino acid balance than earthworm.

According to data by Istiqomah et al. (2009) and other authors, earthworm meal of L. rubellus contains 65,63 % crude protein, earthworm meal of L. terestris contains 32,60 % crude protein, earthworm meal of P. excavatus contains 57,20 % crude protein and have complete amino acids. Dynes (2003) gives the similar results on crude protein in earthworm meal of Eisenia andrei and E. foetida.

Silage

Earthworms (E. foetida and L. rubellus) have been ensiled with sorghum and molasses in the following proportions: 1) 60% earthworms, 40% sorghum; 2) 60% earthworms, 40% sorghum, adjusting pH to 4,0 with HCl; 3) 60% earthworms, 20% sorghum, 20% molasses; 4) 60% earthworms, 20% sorghum, 20% molasses, adjusting pH to 4,0 with HCl (Ortega Cerrilla et al., 1996). These four mixtures have been allowed to ferment for 15 days at 18^o C. No essential differences are in the percentage of moisture, ether extract, crude fiber and crude protein for treatments 1, 2, 3 and 4, respectively, hence Ortega Cerrilla et al. (1996) conclude that it is possible to preserve earthworms E. foetida and L. rubellus by ensiling, adding carbohydrates like sorghum or molasses, and that an addition of acids to have an adequate fermentation is optional.

Vermicomposts

Basically, vermicomposts contains cow, horse and other manure, agricultural waste, tree leaves and other vegetable byproducts, processed by earthworms, together with the ... Read more »

Comparative chemical composition of two freshwater sludgeworms, Tubifex tubifex and Limnodrilus hoffmeisteri, has been studied by Whitten & Goodnight (1982). These authors have found, in particular, that L. hoffmeisteri contain the significantly greater amount of lipid soluble material than T. tubifex. Graney et al. (1986) have measured the concentrations of free amino acids in five species of freshwater sludgeworms (L. hoffmeisteri, T. tubifex, Potamothrix moldaviensis, P. vejdovskyi and Stylodrilus heringianus). Alanine, represented between 23,1 % and 41,8 % of the total free amino acid pool, has been found to be most abundant in all species.

Chemical composition of T. tubifex is determined by Saglio et al., (1990) in the context to study the  attractiveness of amino acids to fish.. Basic amino acids such as lysine (12,0 mg l⁻¹), histidine (9,1 mg l⁻¹) and arginine (8,1 mg l⁻¹) as well as non-polar amino acid such as alanine (11,7 mg l⁻¹) are most abundant in the crude tubifex extract (500 mg l⁻¹).

According to Yanar et al. (2003), the most abundant amino acids (g per 100 g protein) in T. tubifex are lysine (6,54), leucine (6,52) and argenine (5,39). On the crude protein content (% of dry matter), T. tubifex (58,68 %) is near to enchytraeid worms, Enchytraeus sp., and brine shrimp, Artemia salina, but lags behind cladocerans, such as Daphnia sp. and Moina sp., as well as copepods, such as Tigriopius japonicus and Acartia clausi (from 70,09 % to 72,13 %). Total fatty acid content is 7.28 mg per 100 mg dry weight, ω-3 and ω-6 fatty acids compose 18 % and 22 % of the total, respectively (Yanar et al., 2003).

T. tubifex can be considered as the caratenoid source with the total carotenoids measured at the level of 15,02 mg kg^-1 (Yanar et al., 2003). This amount is close to the value (about 40 mg kg^-1) needed in diet of fish to ensure their pigmentation (e.g., Christansen & Wallace, 1988; Choubert & Storebakken 1989).

Attractiveness

Accordung to Saglio et al., (1990), the crude tubifex extract is significantly attractive for common carp, Cyprinus carpio, in the range of concentrations tested (5 mg l⁻¹, 50 mg l⁻¹, 500 mg l⁻¹, 5 g l⁻¹). Maximum attraction is obtained in response to the extract with concentration of 500 mg l⁻¹.

Experimental tests of the four chemical groups of amino acids show that acidic amino acids (aspartic and glutamic) do not produce significant activity in carp. Basic amino acids (lysine, histidine and arginine) as well as polar, uncharged amino acids (glycine, serine, threonine, tyrosine, asparagine and glutamine) are ineffective as attractants but significantly increase exploratory behaviour in carp. Non-polar amino acids (alanine, valine, leucine, isoleucine, phenylalanine and methionine) show significant effects on both attraction and exploration.

Saglio et al., (1990) have found that combination of alanine, valine and glycine acts similar to the crude tubifex extract. To match the dose of 500 mg l⁻¹ of the crude tubifex extract, concentrations of alanine, valine and glycine are 1,3 x 10^-7 mol l⁻¹, 5,7 x 10^-8 mol l⁻¹ and 5,0 x 10^-8 mol l⁻¹, respectively.

For camparison, an extract of pupa silkworm, Bombyx mori, contains more acidic amino acids (27,1%) (Tsushima & Ina, 1978) than an extract of sludgeworms (10,9%). According to experimental findings by Kasumyan & Morsi (1996), asparttic and glutamic acids are attractive (after cysteine and proline) for C. carpio as gustatory stimulants.

Basic References