Prey selection and functional morphology through ontogeny of Amphiprion clarkii with a congeneric comparison

The relationship between the complexity of the feeding apparatus and prey selection through ontogeny was examined in Amphiprion clarkii larvae. Larvae were reared from 1 to 10 days post-hatch (dph) on a diet of rotifers, wild-caught plankton and newly hatched Artemia sp. nauplii. Results were compared with available data on the relationship between functional morphology and prey selection of Amphiprion frenatus to establish patterns of functional morphology and prey selection between the larvae of two species of coral-reef fishes. Larvae of both species exhibited an increase in selection of larger prey through ontogeny coincident with an increase in the complexity of the feeding apparatus. The first elements to ossify in larvae of both species were the pharyngeal teeth ( A. clarkii : 5 dph, near ± s.d. Standard length, L _S,4· 3 ± 0· 2 mm; A. frenatus : 5 dph, L _S5· 0 ± 0· 4 mm) which, in combination with the development of a more functional feeding apparatus, may have permitted larvae to better process new types and sizes of prey. Prey items, however, were selected differentially between the two fish species, which could not be fully explained by the functional state of the feeding apparatus. While prey selection is influenced by the functional state of the feeding apparatus, all aspects of larval fish biology (morphology, behaviour and physiology) should be considered.     

Effects of live food and formulated diets on survival, growth and protein content of first-feeding larvae of Plelteobagrus fulvidraco

In recent years, much progress has been made in the rearing of fish larvae fed only artificial diets. A preliminary study was made in an attempt to evaluate the effects of live food and formulated diets on survival, growth and body protein content of first‐feeding larvae of Plelteobagrus fulvidraco. Three test diets varying in protein level were formulated: Feed 1 containing 45% protein, Feed 2 with 50% protein and Feed 3 with 55% protein. Larvae fed live food (newly hatched Artemia, unenriched) were the control. The experiment started 3 days post‐hatch and lasted for 23 days. At the end of the 23‐day trial, survival was best in the control group (65.6%) whereby the final body weight and specific growth rate (SGR) were significantly lower than those in the test feed groups. At the same time, coefficients of variation for SGR and final body weight in the test groups were significantly higher than those in the control. Whole body protein content in all treatments showed a similar tendency during development: significantly higher 3 days post‐hatch, then decreasing significantly, and then increasing unstatistically 10 days post‐hatch. All results suggest that live food is still better for first‐feeding larvae of P. fulvidraco, since live food leads to healthier larvae growth.     

Feeding behaviour,feed selectivity and growth studies of mangrove killifish, <Emphasis Type="Italic">Kryptolebias marmoratus</Emphasis>, larvae using various live and formulated feeds

Nine types of live foods viz. L, S and SS morphotypes of Brachionus plicatilis sp. complex, first instar Artemia franciscana, Fabrea salina, Acartia tsuensis, Tigriopus japonicus, Diaphanosoma celebensis, Moina mongolica and a formulated feed of two sizes (400 and 700 μm) were used to observe feeding behaviour and growth of mangrove killifish, Kryptolebias marmoratus. Behavioural observations were made for one hour on days 0, 1, 5, and 10 after hatching. Focus, unsuccessful and successful attacks and vomit were noted. With rotifers L, S and SS types and newly hatched Artemia nauplii as food, all the larvae showed maximum feeding success throughout the experimental period. Larvae did not consume any of the 700 μm artificial diet. Vomiting was noticed on capturing the ciliate Fabrea and 400 μm artificial diets. Rotifers were ingested in greater numbers. SS-type rotifers were consumed in largest number (209.2/h per individual) on day 10. Significantly greater growth was observed after 10 days rearing with L type rotifer, Artemia nauplii, T. japonicus, A. tsuensis, M. mongolica, D. celebensis, and a mixture of L type rotifer and F. salina (Tukey–Kramer post hoc test, P < 0.05). Feed selectivity experiments on days 0, 1, 5 and 10 revealed that killifish larvae feed preferentially on Artemia nauplii and rotifers from a mixture of Artemia nauplii, rotifers, A. tsuensis, T. japonicus, D. celebensis and M. mongolica. Techniques for culturing various zooplankton at small-scales are also described.     

Growth response of African catfish,Clarias gariepinus (B.), larvae and fingerlings fed protease‐incorporated diets

African catfish, Clarias gariepinus (B.), is one of the promising freshwater fish species in African aquaculture but the expansion of its farming needs more production of its larvae. The use of live food organisms at first feeding for larvae is still obligatory. That increases the cost of larvae production. Hence, the incorporating of exogenous enzymes especially protease in artificial microdiets may provide affordable alternatives for enhancing the larvae performance. The present study was carried out to evaluate the growth and survival of larvae or fingerlings of African catfish fed artificial diets incorporated with different protease levels. Four artificial diets were formulated and enriched with protease enzyme at levels of 0.0, 750, 1,000, and 1,250 unit/kg diet; after that diets were made into crumbles (100–200 µm diameter). After absorption of the yolk sac, diets were offered to fish larvae (3.6 ± 0.2 mg) in triplicates as a starter feed up to apparent satiation every two hours for 30 days. In another treatment, fish larvae were fed on newly hatched Artemia nauplii (2,500 Artemia/L) as a starter food. In another experiment, African catfish fingerlings (10.1 ± 1.6 g) were fed on the same diets up to satiation twice a day for 2 months. It was noticed that the dietary protease improved larval growth and survival but not as Artemia nauplii did where fish larvae fed on Artemia nauplii showed highest growth and survival followed by those fed a diet enriched with 1,250 unit/kg diet of protease. The mortality of larvae fed protease‐enriched diets as well as the control diet was occurred mostly at the first week reaching its maximum at the third week. The poor growth was observed with fish larvae fed the control diet. Meanwhile, catfish fingerlings fed protease‐enriched diets showed higher growth over those fed the control diet. The larvae survival (11.0%–41.7%) was enhanced by increasing protease levels and it was lower than that of fingerlings (95.6%–100.0%). Furthermore, protein retention and digestibility were significantly improved with protease supplementation over the control diet especially at a level of 1,000 unit/kg diet. As compared with the previous studies, live food should be used in larvae rearing for the first week after that a starter diet enriched with protease at levels of 1,250 unit/kg diet should be used. In case of fish fingerlings, the dry diets should be enriched with 1,100 unit/kg diet to improve diet digestibility and subsequently enhance their growth.     

Larval rearing of burbot (Lota lota L.) using Brachionus calyciflorus rotifer as starter food

Burbot Lota lota L. is one of the endangered freshwater fish species in western Europe for which the development of controlled larval rearing procedures could produce enough material for stock enhancement. The suitability of the freshwater rotifer Brachionus calyciflorus as a start food for larviculture of burbot was investigated. After yolk‐absorption, the larvae were stocked in 40‐L tanks under different feeding conditions: clear water rearing conditions with rotifers (Brachionus calyciflorus) for 10 days (R), green water conditions (Chlorella sp.) with rotifers offered for 10 days (MALR), green water conditions (Chlorella sp.) for 3 days followed by clear water in combination with rotifer feeding for 7 days (AL3R), and clear water conditions with Artemia nauplii offered for 10 days (Art). After the 10‐day feeding, all groups received Artemia nauplii up to 35 days post‐hatching. Larval survival was counted at day 10 and at the end of the 35‐day rearing experiment. At day 35, a significant survival difference was noted between the groups where rotifers were supplemented with algae vs only Artemia. At the end of the experiment, the highest survival rate (69.20%) was obtained with larvae receiving only algae in the first 3 days of feeding. Lowest survival rate (24.90%) was obtained with larvae receiving only Artemia for 35 days. This indicates that smaller prey are essential for burbot at first feeding. Larval length and wet weight were measured at the time of mouth opening, at days 7, 10, and 21, and at the end of the experiment (day 35). On day 35, mean length of the larvae varied significantly between the treatments. However, the final wet weight of the larvae did not vary significantly between the treatments.     

Growth and survival of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed isocaloric diets with different protein levels during weaning

The growth of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed four isocaloric diets (4200 kcal kg^?1) with different protein levels during weaning was determined. Diets containing 45, 50, 55, and 60% protein were formulated by linear programming using amino acid profiles based on that of 2‐day‐old river catfish larvae. Artificial diets were fed to the larvae beginning at day 5 after being initially fed Artemia nauplii for 4 days. The larvae thrived solely on artificial diets from day 8 to day 16. On the other hand, the control larvae were fed Artemia nauplii from day 1 to day 16. Results of the feeding trial showed that growth and survival of M. nemurus larvae given the diet containing 60% protein were high and comparable to those of the larvae given only live food (control). Larvae fed the 55% protein diet had significantly lower growth and survival than the larvae on the control and 60% diets but significantly higher growth and survival rates than did larvae fed with 45 and 50% protein diets. Carcass moisture and total lipids after 16 days of feeding did not differ significantly (P > 0.05), but body protein increased with increasing dietary protein. Body protein of the control larvae was similar to that of larvae given the 60% protein diet.     

Larval rearing of chub, Leuciscus cephalus (L.), using decapsulated Artemia as direct food

Little is known about the larviculture of the chub, Leuciscus cephalus (L.), an endangered cyprinid species endemic to European flowing waters. The use of decapsulated Artemia cysts as food for chub larviculture was investigated. After 3‐day feeding with the rotifer Brachionus calyciflorus, the larvae were fed on different diets: (i) dried decapsulated Artemia cysts, (ii) Artemia nauplii, (iii) rotifers for seven more days and then Daphnia collected from a pond, and (iv) an artificial diet. After a 24‐day rearing period, the highest survival rate was obtained with the larvae receiving decapsulated Artemia cysts. Feeding of the larvae with an artificial diet resulted in a significantly lower survival rate compared with the other groups. At the end of the experiment, the larvae fed on Artemia nauplii yielded a significantly higher mean length compared with the other groups. Feeding an artificial diet resulted in a significantly lower average weight and mean length gain compared with the other groups.     

Methodical aspects of rearing decapod larvae,Pagurus bernhardus (Paguridae) andCarcinus maenas (Portunidae)

Improved methods for experimental rearing ofPagurus bernhardus andCarcinus maenas larvae are presented. Isolated maintenance was found essential for reliable statistical evaluation of results obtained from stages older than zoea-1. Only by isolated rearing is it possible to calculate mean values ±95% confidence intervals of stage duration. Mean values (without confidence intervals) can only be given for group-reared larvae if mortality is zero. Compared to group rearing, isolated rearing led to better survival, shorter periods of development and stimulated growth. Due to different swimming behaviorP. bernhardus zoeae needed larger water volumes thanCarcinus maenas larvae.P. bernhardus zoeae were reared with best results when isolated in Petri dishes (ca. 50 ml). They fed on newly hatched brine shrimp nauplii (Artemia spp.).P. bernhardus megalopa did not require any gastropod shell or substratum; it developed best in glass vials without any food.C. maenas larvae could be reared most sucessfully in glass vials (ca 20 ml) under a simulated day-night regime (LD 16:8); constant darkness had a detrimental effect on development, leading to prolonged stage-duration times.C. maenas larvae were fed a mixture of newly hatched brine shrimp naupli and rotifers (Brachionus plicatilis).     

Preliminary investigation of feeding performance of larvae of early red-spotted grouper, Epinephelus coioides, reared with mixed zooplankton

Larvae of red-spotted grouper, Epinephelus coioides, were reared inoutdoor tanks with nauplii of copepods (mainly Pseudodiaptomus annandaleiand Acartia tsuensis) and/or rotifers, Brachionus rotundiformis. Grouperlarvae successfully started feeding on early stage nauplii even though theirabundance was as low as approximately 100 individuals l^–1 andshowed better survival and growth thereafter compared to those fed withrotifers only. Incidence of feeding reached 100% on day 4 whennauplii were available and only on day 9 when rotifers were given alone.Larvae seemed to be poor feeders at the onset of feeding, attempting tocapture any food organisms in the tank water. Selective feeding ability oflarvae started from day 4 and the larvae then preferred to feed on medium-and large-size nauplii rather than on rotifers as they grew. Larvae appearedto have a better chance at surviving in the presence of early stage nauplii,which were probably caught more easily than rotifers.     

Rearing tench (Tinca tinca L.) larvae on live feed (Artemia) and on two transition schedules from live to dry diets

Two 60‐day experiments were carried out on tench (Tinca tinca L.) from day 5 post‐hatch. Density was 20 larvae L^?1 and temperature 24 ± 0.5°C. In experiment 1, Artemia nauplii were the sole food, testing nauplii amounts and feeding frequency. High survival rates (between 79.5% and 95.5%) were obtained. Growth was faster as nauplii amounts were greater; the highest growth rate (11.00), weight (265.5 mg) and Fulton’s coefficient (1.40) were obtained when fish were fed in excess once a day, without significant differences from the growth obtained by feeding in excess of eight times a day. In experiment 2, a dry diet for marine fish was tested as a replacement for Artemia nauplii, following two transition protocols, one faster than the other; high survival rates (between 77.7% and 87.1%) were again obtained. The slower transition allowed a growth rate of 10.14, length of 23.1 mm, weight of 158.3 mg and a Fulton’s coefficient of 1.28, without significant differences from the faster transition. At all stages, growth values were significantly higher from feeding nauplii in excess as the sole food, but the required nauplii quantity was six times higher than the amount supplied to the animals fed the dry diet.     

Veligers of an introduced bivalve,Limnoperna fortunei,are a new food resource that enhances growth of larval fish in the Paraná River (South America)

1. Larvae of ‘sábalo’, Prochilodus lineatus, whose adults represent over 60% of overall fish biomass in the Río de la Plata Catchment, have been observed to feed intensively on veligers of the exotic bivalve Limnoperna fortunei. 2. To assess the effects of this dietary shift on the growth of P. lineatus, 28‐day laboratory experiments were carried out feeding newly hatched P. lineatus larvae with three diets: zooplankton artificially enriched with L. fortunei veligers; natural zooplankton; and zooplankton artificially enriched with cladocerans and copepods. The average length, weight and gut contents of the fish larvae were assessed weekly and metabolic rates of fish larvae were measured. 3. Proportions of veligers in gut contents were always higher than those in the experimental diet: 100, 76 and 21% for veliger‐enriched, natural and low‐veliger diets, respectively. Larvae fed a veliger‐enriched diet grew to a significantly larger size than larvae fed the other two diets. In energetic balance comparisons using metabolic rates and prey energy content, all three diets were sufficient to support metabolism and growth. The greatest values of excess energy at the end of each week were in the veliger‐enriched experiments. 4. Feeding on veligers of L. fortunei significantly enhances the growth of P. lineatus larvae and supports the idea that this new and abundant resource is selectively preyed upon by P. lineatus during its larval stage. Higher growth rates may stem from the higher energy contents of veligers compared to crustaceans and/or from the lower energy costs of capturing slower prey.     

Trypsin activity and physiological aspects in larval rearing of European sea bass (Dicentrarchus labrax) using live prey and compound diets

The aim of this study was to evaluate the potential of a compound diet as a live prey substitute for feeding European sea bass larvae ( Dicentrarchus labrax L.). The effect of a commercial diet (Nippai ML feed) and live prey ( Artemia nauplii) on tryptic enzyme activity, protein content, growth (standard length) and survival rates of sea bass larvae were tested during a 27-day rearing experiment. Sea bass larvae were divided into two groups. The live food group (control group) was fed exclusively on newly hatched Artemia nauplii (Inve AF grade), the test group was fed exclusively with the compound diet from day 15 onwards. As trypsin has been demonstrated to be a useful indicator for evaluating digestibility of food and the nutritional condition of fish larvae, individual tryptic enzyme activity was determined in both feeding groups. Larvae older than 14 days after hatching and fed on live food showed a significantly higher tryptic enzyme activity than larvae fed the compound diet. A similar relationship between tryptic activity and standard length in both test groups was detected only in small larvae (standard length < 7 mm). The usefulness of proteolytic enzyme activity measurements in larval fish research, as well as its use in aquaculture nutrition research, was confirmed. Protein content, increase in length and survival rates of the sea bass larvae were additionally determined in order to evaluate an influence on the diet. The protein content of larvae fed the Artemia nauplii was higher and the growth of larvae fed the compound diet was reduced. Larval mortality was not affected by the diet given.     

Nonvisual feeding in a visual planktivore,Xenomelaniris venezuelae

Summary Studies of the diel feeding patterns of the planktivorous fish, Xenomelaniris venezuelae, in Lake Valencia, Venezuela, revealed that, although the fish is primarily a diurnal feeder, it consumes substantial numbers of Chaoborus larvae and pupae at night. A number of fish species are known which feed on plankton at night, but these fish are filter feeders and their diets largely consist of relatively small, nonevasive prey. Chaoborus, however, is large and agile. Predation by Xenomelaniris in the dark was also studied experimentally. Captured fish were placed in completely darkened aquaria with zooplankton from Lake Valencia. After several hours the plankton was removed and examined for evidence of feeding. The fish were found to consume Chaoborus pupae and fourth instar larvae but not other types of prey. The mode of feeding by Xenomelaniris in the dark is unknown.     

Temperature and laboratory feeding rates in Carcinusmaenas L. (Decapoda: Portunidae) larvae from hatching through metamorphosis

Larvae of Carcinus maenas L. were reared in the laboratory and temperature-dependent stage durations of successive instars were examined at 12, 15, 18, and 25°C. Feeding rates (FR), in numbers of newly hatched Artemia nauplii, biomass, and energy consumed by a single crab larva during 24 h, were measured daily through the moulting cycles of all larval stages at the four temperatures. Dry weight (DW) and elemental content of carbon (C), nitrogen (N) and hydrogen (H) were analysed in newly hatched (0 h) and 1-day-old (24 h) Artemia nauplii at six temperatures (6, 9, 12, 15, 18, 25°C). Due to a 24 h feeding regime, the temperature dependent “mean nutritive value” of newly hatched brine shrimp nauplii is defined, individual biomass (DW, C, N, H) and energy (Joule) 12 h after hatching. General figures in changing individual daily FR, and temperature-dependent peculiarities are discussed. The total amount of food ingested by successive larval instars increases exponentially, while the increasing cumulative quantity consumed by individual crab larvae on successive days of development is described by power functions. At higher temperatures significantly less absolute biomass and energy is consumed during the entire larval development. C. maenas megalops are the main energy consumers in larval life, contributing 41 to 67% (12 to 25°C) to the total larval energy intake between hatching and metamorphosis. Larval ability to adapt to increasing metabolic costs for maintenance in higher water temperatures is discussed with average daily feeding rates (AFR). Improved efficiencies are presented for the cumulative larval energy budget, 31% in assimilation, and 4.4% in gross growth (K₁).     

Mariculture of kurosoi,Sebastes schlegeli

Synopsis The technology of collecting developing larvae from female kurosoiSebastes schlegeli, and raising the larvae to juveniles (100 mm total length (TL)) to be released into the oopen sea, is presented. Gravid females 40–46 cm TL were captured in May–June 1977–1980 and held in the laboratory until parturition. Fecundity of fish in this size range was 100 000–184 000. Larvae were sequentially fed rotifers,Artemia nauplii, and young sand lance,Ammodytes personatus, until reaching 25 mm; this required 35 days and yielded a survival rate of 50%. Thereafter, the fish were reared in separate size groups to avoid cannibalism. Minced or chopped sand lance and commercial food were provided until the final size of 100 mm was attained. The growth of juvenile kurosoi from 25 to 100 mm required 85 days, with a survival rate of 90%. The effect of released cultured fish on the local stock is being determined from information on the recapture of tagged fish.     

Rotifers as food in aquaculture

The rotifer Brachionus plicatilis (O.F. Muller) can be mass cultivated in large quantities and is an important live feed in aquaculture. This rotifer is commonly offered to larvae during the first 7–30 days of exogenous feeding. Variation in prey density affects larval fish feeding rates, rations, activity, evacuation time, growth rates and growth efficiencies. B. plicatilis can be supplied at the food concentrations required for meeting larval metabolic demands and yielding high survival rates. Live food may enhance the digestive processes of larval predators. A large range of genetically distinct B. plicatilis strains with a wide range of body size permit larval rearing of many fish species. Larvae are first fed on a small strain of rotifers, and as larvae increase in size, a larger strain of rotifers is introduced. Rotifers are regarded as living food capsules for transferring nutrients to fish larvae. These nutrients include highly unsaturated fatty acids (mainly 20: 5 n–3 and 22: 6 n–3) essential for survival of marine fish larvae. In addition, rotifers treated with antibiotics may promote higher survival rates. The possibility of preserving live rotifers at low temperatures or through their resting eggs has been investigated.     

Feeding by larvae of Hypoatherina tropicalis (Pisces: Atherinidae) and its relation to prey availability in One Tree Lagoon,Great Barrier Reef,Australia

Synopsis Feeding of and food availability for larvae of Hypoatherina tropicalis were investigated in One Tree Lagoon, Great Barrier Reef, Australia, during November 1981 and January 1982. These surface-dwelling larvae and their microzooplankton prey were sampled as near to simultaneously as possible on 12 occasions during the daytime. Larvae of all sizes (5–17 mm SL) fed successfully over the observed range of mean prey densities (12–235 per liter), and the overall feeding incidence was 98.9%. Larger larvae consumed greater numbers and more categories of prey than did smaller larvae. Larvae selected copepods of all sizes, and nauplii, gastropods, bivalves, and foraminiferans that were greater than 75 ¢s mm in width. Tintinnids (mostly 37–74 µm in width) were generally avoided by larvae, but were occasionally important in the diets when they constituted more than 60% of the total available prey, regardless of the density of the selected prey categories. Larvae less than 14 mm SL ingested meroplankton (gastropods, bivalves, foraminiferans, and polychaetes) in direct relation to the densities available, and without regard to the densities of copepods available. However, the largest larvae (14–17 mm SL) ingested meroplankton in inverse relation to the density of copepods available, indicating that larvae consumed more meroplankton when the concentration of copepods was low. Such flexibility and opportunism in feeding behavior may increase the larvae's chances of obtaining adequate nutrition during periods of suboptimal feeding conditions.     

Harmful dinoflagellate Cochlodinium polykrikoides impairs the feeding behavior of larval sheepshead minnows (Cyprinodon variegatus)

Research evaluating the toxicity of the harmful dinoflagellate Cochlodinium (a.k.a. Margalefidinium) polykrikoides has been dominated by acute bioassays while the sublethal effects remain less well understood. This study examined the sublethal effects of C. polykrikoides exposure on the feeding behavior of larval estuarine fish. Sheepshead minnow (Cyprinodon variegatus) larvae were used in feeding experiments which assessed the total consumption of zooplankton prey (i.e., Artemia nauplii) over defined time periods. Larvae exposed to intermediate concentrations (i.e., 10² cells ml⁻¹) of clonal cultures of C. polykrikoides saw statistically significant reductions (range = 10%–81%) in the Artemia consumed compared to controls (i.e., filtered seawater, culture media or nontoxin producing dinoflagellate). These reductions were found independent of whether the larvae were fed or starved prior to experimentation. As these concentrations are similar to those typically found during mild blooms or at the periphery of dense blooms, these findings have significant implications for the feeding behavior of ichthyoplankton.     

Feeding behaviour of Japanese flounder larvae under laboratory conditions

Tank–reared Japanese flounder larvae, Paralichthys olivaceus , had a major feeding peak in the morning and a secondary peak in the afternoon throughout the larval development, with light being the primary factor regulating their feeding activity. The larvae consumed rotifers in preference to Artemia for up to 10 days, after which the food preference shifted to Artemia . Feeding rates of the larvae prior to 10 days post–hatch depended on prey density, but in the old larvae, feeding rates were independent of prey density. Maximum feeding rate occurred at 19° C. The occurrence of the attack posture, after its onset at first feeding (2 days post–hatch), increased up to 25 days, began to decrease when the larvae prepared to settle down, then disappeared after settlement. The occurrence frequency of the attack posture was positively related to fish density, but inversely related to starvation duration, and occurred most frequently at 19° C. This posture depended on prey density in larvae prior to 10 days post–hatch, but became independent of prey density as the larvae developed. It was obvious that, for flounder larvae, attack posture was a behavioural character closely related to feeding and subject to larval development and environmental factors.     

Early development of New Zealand hapuku Polyprion oxygeneios eggs and larvae

This study describes for the first time the normal development of New Zealand hapuku Polyprion oxygeneios embryos and larvae reared from fertilization to 11 days post-hatch (dph) at a constant temperature. Fertilized eggs were obtained from natural spawnings from communally reared captive wild broodstock. Eggs averaged 2 mm in diameter and had single or multiple oil globules. Embryos developed following the main fish embryological stages and required an average of 1859·50 degree hours post-fertilization (dhpf) to hatch. The newly hatched larvae (4·86 mm mean total length, L(T) ) were undifferentiated, with unpigmented eyes, a single and simple alimentary tube and a finfold that covered the entire body. Larvae relied on the energy from the yolk-sac reserves until 11 dph (7·33 mm mean L(T) ), when yolk-sac reabsorption was almost completed. Some of the major developmental stages from hatching to yolk-sac reabsorption were eye pigmentation (5 dph), upper jaw formation (7 dph), lower jaw formation (8 dph) and mouth opening (8-9 dph). By 9 dph, the digestive system consisted of pancreas, liver, primordial stomach, anterior and posterior gut; therefore, P. oxygeneios larvae would be capable of feeding on live prey. The developmental, morphological and histological data described constitutes essential baseline information on P. oxygeneios biology and normal development.