Spawning Egg Research Articles

Size distribution of the Late Devonian ammonoid Prolobites: indication for possible mass spawning events

Worldwide, the ammonoid genus Prolobites is only known from a few localities, and from these fossil beds almost all of the specimens are adults as shown by the presence of a terminal growth stage. This is in marked contrast to the co-occurring ammonoid genera such as Sporadoceras, Prionoceras, and Platyclymenia. Size distribution of specimens of Prolobites from three studied localities show that, unlike in the co-occurring ammonoid species, most of the material belongs to adult individuals. The morphometric analysis of Prolobites delphinus (Sandberger & Sandberger 1851) demonstrates the intraspecific variability including variants with elliptical coiling and that dimorphism is not detectable. The Prolobites material shows close resemblance to spawning populations of Recent coleoids such as the squid Todarodes filippovae Adam 1975. Possible mass spawning events are discussed in the context of the size distribution and limited geographic range of Prolobites. Finally, the potential fecundity and brooding behaviour of Prolobites is hypothesized using the examples of post spawning egg care in Recent coleoids.

Reproductive cycle and ovarian development of the marine ornamental shrimp Stenopus hispidus in captivity

The reproductive cycle and ovarian development of the marine ornamental shrimp Stenopus hispidus were described starting from adult mating pairs under laboratorial conditions. The pairs were individually kept in aquaria under constant conditions of salinity (35‰), temperature (26 ± 0.5 °C) and photoperiod (12L:12D). Molting, mating, spawning and hatching were recorded during three consecutive reproductive cycles. Females at different stages of ovarian development were anesthetized and their ovaries were removed, photographed, fixed and processed for histological examination. Mating occurred after female molting. Mean incubation time was 22.8 ± 2.1 days and mean intermolt periods were 25.5 ± 2.3 days for females and 26 ± 4.1 days for males. The ovaries varied in size and color during each reproductive cycle, which could be clearly seen through the transparent carapace. Spent ovary (translucent), lasted for 3 days after egg spawning; developing ovary (white), lasted 7 days; developed ovary (light green), between 5 and 8 days and advanced ovary (dark green) lasts 10 to 13 days. Microscopically, the ovarian stages differed in proportion of follicular cells, oocytes and oogonia. Follicular cells were abundant and mature oocytes were absent at the spent stage, while the number and size of secondary oocytes increased gradually thereafter. The present study indicates that S. hispidus can undergo multiple reproductive cycles under culture conditions. The changes in the macroscopic appearance of the ovary are strongly associated with the reproductive cycle.

How newly recruited cohorts are formed in the trochid gastropod population ( Umbonium moniliferum) on an intertidal sandflat in western Kyushu, Japan

In macrobenthos with meroplanktonic larvae, larval settlement and recruitment are two crucial processes for population cohort formation, yet only a few studies have given explicit definitions for newly settled and recruited juveniles (settlers and recruits) and descriptions of those processes with relevant time scales. Using a comprehensive approach, our study demonstrated a clear pattern in cohort formation of the trochid gastropod population ( Umbonium moniliferum) on an intertidal sandflat, southwestern Japan, in the breeding seasons of 2002 and 2007–2009. The study included (1) daily monitoring for spawned eggs and competent larvae in the field and the laboratory, (2) daily and fortnightly monitoring for juveniles, and (3) collection of larvae in the water column and in situ simulation of larval retention, releasing drift cards within an embayment embracing the sandflat. The population with shell widths of 5–14 mm occupied the lower shore in densities of about 1000 inds. m − 2 , spawning gametes for lecithotrophic larval development with the shortest duration of 3 d during late September through October. The settlers occurring per day and the newly recruited cohort in the size–frequency distribution were defined as juveniles belonging to the smallest size class (0.20 and 0.21 mm) and to the most left-hand normal-distribution group, respectively. The growth rate was estimated at 0.02 mm d − 1 . A synchronous mass egg spawning took place 2–4 d after neap tide, followed by the sequential occurrence of veligers and settlers in high densities, which was completed by the next neap tide, leading to the formation of one newly recruited cohort. Three distinct cohorts were produced consecutively, most probably due to this semilunar cycle. The iteroparous spawning was supposedly performed by the same females. By the following spring, the three cohorts had fused into a single young-of-the-year cohort. Veligers were present across all depth layers in the water column down to 20 m, with a quarter being present within the surface 1 m. Drift cards were driven ashore, with cumulative retrieval rates of 50 and 70% 3 and 9 d after release, respectively, suggesting that hydrodynamics allowed good retention of larvae in the water surface. Using an exponentially decreasing function describing competent larval numbers in a 2 to 9-d period after fertilization in the laboratory, the degree of self-recruitment in the population was assessed under the assumption of complete retention and no mortality of larvae due to predation. The results suggested the presence of some allochthonous subsidy.

Effects of Salinity on the Reproductive Cycle of Female Freshwater Shrimp, Palaemonetes argentinus

The South American shrimp Palaemonetes argentinus inhabits inland freshwater habitats such as lakes, rivers and streams, but also coastal brasckish marshes and lagoons. Hence, this so-called “freshwater” shrimp is expected to be able to reproduce in a wide range of salinities. Here we examined effects of three salinities (1, 15, 25 ppt) on survival and reproductive cycle of females originating from two separate populations in Argentina: 1) Lake Chascomús (LC), a shallow inland lake with low and stable ionic concentrations; and 2) Vivoratá Creek (VC), a lotic stream draining into the adjacent brackish lagoon Mar Chiquita, where salinity is tide-dependent. After an observation period of four months, survival was generally high, without showing significant differences between salinities or populations. Ovarian maturation was measured on a scale ranging from “empty” ovaries (= females with newly laid eggs) to fully developed ovaries (= females ready to spawn). Most LC shrimps (> 80%) developed their ovaries again after an initial egg extrusion (beginning of the experiment) and produced new eggs at all tested salinities. In VC shrimps, ovarian maturation and egg deposition were successful in both the lowest and the highest salinity (1, 25 ppt), but developed ovaries were resorbed in most individuals at the intermediate salinity (15 ppt). Ovarian resorption was never observed at the highest salinity treatment, thus this phenomenon may have been provoked by unknown factors other than ionic concentration. At 15 and 25 ppt, the beginning of vitellogenesis started later and the total time to ovary maturation was longer than at 1 ppt, lengthening in both populations the time between consecutive spawning of eggs by nearly 10 days. Irrespective of the origin of a population, female P. argentinus survived and completed all reproductive events under a wide range of salinities, which supports the hypothesis that this species is in an early stage of evolutionary invasion of freshwater habitats.

Daily Spawning and Quality of Eggs in One Female Red Sea Bream Pagrus major

Daily Spawning and Quality of Eggs in One Female Red Sea Bream Pagrus major

Spawning and Quality of Eggs of Striped Jack Fed Raw Fish or Dry Pellets with 2% Spirulina

Spawning and Quality of Eggs of Striped Jack Fed Raw Fish or Dry Pellets with 2% Spirulina

Indeterminate Growth of the Fairy Shrimp, Branchinella (Branchinellites) kugenumaensis (Branchiopoda: Anostraca) in an Unpredictable Ephemeral Pool

A major life-history challenge for fairy shrimps (Anostraca) is the unpredictable environment of the ephemeral pool. The duration and predictability of pool inundations affects their life history strategy. The growth and reproduction schedule of a thamnocephalid fairy shrimp, Branchinella(Branchinellites) kugenumaensis, in an unpredictable ephemeral pool in northern Taiwan was monitored from 2004 to 2008. A total of 15 inundation episodes, resulting from typhoons or, occasionally, frontal systems, was recorded over the five-year period. Thirteen episodes lasted no more than 2-3 weeks. Two exceptionally long inundation periods were caused by additional rain events before the pool dried out. We recorded the growth patterns, egg spawning time, and clutch size of each fairy shrimp cohort during each inundation episode. No significant differences were observed in either growth or reproductive pattern from hatching to first spawning between short and long inundation episodes. The fairy shrimps stopped increasing in size during the first clutch production. Upon subsequent rainfall before the pool dried, the shrimp stopped reproducing and resumed growth, demonstrating a discontinuously indeterminate growth pattern, before resuming egg production. Body length was positively correlated with clutch size, and this can be expressed as|$clutch{\rm{ }}size{\rm{ = 0}}{\rm{.0059 }} \times {\rm{ }}body{\rm{ }}length{{\rm{ }}^{{\rm{3}}{\rm{.165}}}}{\rm{.}}$|⁠. The potential reproductive fitness of this indeterminate growth strategy demonstrates optimal resource allocation between growth and reproduction.

Spawning and Development of Larvae and Juveniles of the Rare Blue Mauritius Angelfish, Centropyge debelius (1988), in the Hatchery

Abstract This study documents the rearing and life history stages of the rare blue Mauritius angelfish, Centropyge debelius, from spawning of eggs through sexual maturity. A C. debelius pair was maintained at our facility for 22 mo. The pair was conditioned to spawn for a 4‐mo period in the fall of 2005 and a 4‐mo period in the summer of 2006 using water temperature and photoperiod manipulation. Continuous spawning was achieved at water temperatures between 22 and 24 C and a photoperiod of long day (LD) 13.5:10.5. Over a 124‐d period, the female produced 97 spawns, 59% of which resulted in fertile eggs. The average fecundity per spawn was 237 eggs (range 13–813 eggs). Fertility of all preserved spawns averaged 19.0 ± 19.8%. Larval rearing attempts using wild caught zooplankton and Artemia nauplii resulted in a total of 10 C. debelius juveniles raised through metamorphosis with an average larval survival up through metamorphosis of 0.36%. Three resulting juveniles were raised through sexual maturity. Sexual dichromatism was first observed about 180 d posthatch. A statistical model: Y = (X× 0.32437) − (X2× 0.00043) − 2.004, where Y = total length (mm) and X = number of days in culture, explained 97.6% of the variation in growth (P < 0.001, R2 = 0.976). The development of eggs and larvae was observed to be similar to that of other Centropyge species that have been cultured. Results of this study indicate that the artificial propagation of C. debelius is technically feasible and forms the basis for this report.

Reproduction, growth and stress response in adult red sea bream,Pagrus major(Temminck & Schlegel) exposed to different photoperiods at spawning season

Adult red sea bream, Pagrus major (body weight, 1.0–2.0 kg) was exposed to three photoperiods [12 h light:12 h dark (12L:12D), 16 h light:8 h dark (16L:8D) and 24 h light:0 h dark (24L:0D)] from 2 months before spawning till the end of the spawning season to investigate growth, spawning and stress response. During the spawning season, tanks were checked every morning for spawned eggs. The growth performance in fish under 24L:0D was stimulated with significantly higher feed intake than those under other photoperiods (P 0.05). The results suggest that stimulating the growth performance of red sea bream at reproductive stage with a 24L:0D photoperiod is possible if the fish are subjected to this photoperiod long before the onset of the spawning season.

REPRODUCTIVE PERFORMANCE OF Anodontia philippiana

Objective of this study was to determine reproductive performance of A. philippiana. Samples were collected from the oil affected mangrove mudflat in Pototan, Guimaras, Philippine on September 2007. A. philippiana were induced to spawn using the serotonin method. Only A. philippiana with shell length of approximately 4.0-5.5 cm were induced to spawn. Three pairs of one ripe female and one ripe male were chosen and placed in aquaria with 3 replicates. A 0.3 ml of 4 rnM serotonin solution (Gros et al., 1997) was injected into 1-2 mm of the gonad of both male and female clams using 0.65 x 25-mm bore hypodermic needle attached to a 5 ml plastic syringe during mid until late afternoon. Number of spawned eggs was calculated, and fertilization was conducted. At 47 h, the percentage of normal (D-larvae) veliger relative to the initial number of eggs was calculated (Massapina et aL, 1999). Larvae from each spawner were reared separately in aquaria for several days without feeding in order to estimate survival rates. The number of larvae we re-estimated every 24-h intervals until total mortality. The decrease in the number of larvae per container we re-calculated as the proportion of live larvae from the initial number of larvae (extinction rate) (Narvarte and Pascual, 2003). Result of this study are total Total spawned eggs (x10 (g m) is 86.11±3.80, Fertilization rate (%) is 83.01±3.13, and harching rate is 36.51+8.64, Length of newly hatched larvae (gm) is 135.73±1.96, Number of days to total mortality (after hatching) without feeding is 9-10 days. Keywords: reproductive, Anodotia philippiana

Variation and temporal patterns in the composition of the surface ichthyoplankton in the southern Bay of Biscay (W. Atlantic)

From September 2000 to December 2006, surface plankton samples were collected on a monthly basis, from a station located in the southern Bay of Biscay (43°37N; 1°43W France), near the deep Capbreton canyon. In this paper, the results for the ichthyoplankton assemblage are presented. Among the 62 taxa recorded, only 35 were present in the larval stage whilst only 10 were represented by their eggs. Taxa represented by both stages (eggs+larvae; N=17) had the highest abundance. The presence in the surface plankton assemblage of species, at either or both stage, is interpreted within the context of the bathymetric distribution of species. The maxima in abundance and diversity occurred in February–March, for eggs, and May–June, for larvae. This 3-month time-lag between the stages is proposed to be related to the timing of egg spawning and larval recruitment to the pelagic environment. Mean egg abundances (82.4±29.8 eggs/10 m 2) were 10-fold higher than the larval abundances (7.1±1.8 larvae/10 m 2). Despite pronounced monthly variability, no statistically significant decrease in either egg or larvae abundance was observed during this 6-year study period. Compared with previous published studies, this study shows that the peak in ichthyoplankton diversity occurred two months earlier. In addition, the spawning period occurred over the whole year, even during autumn and winter. Using ordination techniques, the annual sequence appearance of taxa are described at the study site: Gadiforms, Ammodytidae and Pleuronectiforms were present during the winter whilst Sparidae, Blennidae, Labridae and Gobiidae, formed the summer group. Only three species, European anchovy Engraulis encrasicolus, European pilchard Sardina pilchardus and Atlantic horse mackerel Trachurus trachurus were recorded throughout the year.

Effects of Latency Periods and Injection Doses with Carp Pituitary Extract on Spawning Performance and Egg Quality of Asian Catfish, Clarias batrachus (Linn.)

ABSTRACT An experiment was conducted to evaluate the spawning performance and egg quality of Clarias batrachus at variable latency periods (11, 14, 17, 20, and 23 h) and doses of carp pituitary extract (10, 20, 30, 40, and 50 mg/kg). The fish could not be stripped at 11 h latency with 10 or 20 mg carp pituitary extract (CPE). The highest quantity of eggs was obtained at 14 to 23 h latency with 30–40 mg CPE or 50 mg CPE with 14 to 17 h latency, which did not vary significantly (P < 0.05) at a water temperature of 27°C–28.5°C. The eggs did not fertilize and hatch when stripped at 11-h latency period. Over 80% of total eggs stripped from females injected with 30 and 40–50 mg CPE per kg body weight, and stripped at 14 to 23 h and 14- to 17-h latency, respectively, were fertilized. However, the highest (P < 0.05) number of larvae was obtained from females injected with 40 mg CPE and stripped at 14 or 17 h latency periods. Therefore, this CPE dose and 17 h latency period combination was regarded as the best for obtaining the highest number of larvae during induced spawning of C. batrachus.

Natural egg mass deposition by the Humboldt squid (Dosidicus gigas) in the Gulf of California and characteristics of hatchlings and paralarvae

The jumbo or Humboldt squid, Dosidicus gigas, is an important fisheries resource and a significant participant in regional ecologies as both predator and prey. It is the largest species in the oceanic squid family Ommastrephidae and has the largest known potential fecundity of any cephalopod, yet little is understood about its reproductive biology. We report the first discovery of a naturally deposited egg mass of Dosidicus gigas, as well as the first spawning of eggs in captivity. The egg mass was found in warm water (25–27°C) at a depth of 16 m and was far larger than the egg masses of any squid species previously reported. Eggs were embedded in a watery, gelatinous matrix and were individually surrounded by a unique envelope external to the chorion. This envelope was present in both wild and captive-spawned egg masses, but it was not present in artificially fertilized eggs. The wild egg mass appeared to be resistant to microbial infection, unlike the incomplete and damaged egg masses spawned in captivity, suggesting that the intact egg mass protects the eggs within. Chorion expansion was also more extensive in the wild egg mass. Hatchling behaviours included proboscis extension, chromatophore activity, and a range of swimming speeds that may allow them to exercise some control over their distribution in the wild.

Protandric simultaneous hermaphroditism in the shrimps Lysmata bahia and Lysmata intermedia

Abstract. The sexual system of two peppermint shrimps, Lysmata bahia and Lysmata intermedia, inhabiting intertidal fossil coral terraces at Bocas del Toro, on the Caribbean coast of Panama, was examined. Dissections suggested that the population of each species consisted of functional males and functional simultaneous hermaphrodites. Males have cincinulli and appendices masculinae on the first and second pair of pleopods, respectively, gonopores located at the coxae of the third pair of walking legs, and ovotestes with a well‐developed male portion full of sperm, but an undeveloped female portion. Hermaphrodites lacked appendices masculinae and cincinulli. However, they have male gonopores and ovotestes with well‐developed ovaries full of mature oocytes and testes with sperm. When hermaphrodites were maintained in pairs, both molted and spawned eggs (to beneath abdomen) that continued developing after 3 d, demonstrating that hermaphrodites can reproduce as males and inseminate other hermaphrodites acting as females. The possibility of self‐fertilization or parthenogenetic reproduction was tested and disregarded, because hermaphrodites reared in isolation spawned oocytes that failed to develop, disappearing from the abdomen after 2 d. Males reared in pairs mature as hermaphrodites in &lt;50 d, showing the ability of males to mature as hermaphrodites. These results demonstrate that L. bahia and L. intermedia are protandric simultaneous hermaphrodites, as reported for all species of this genus whose sexual system has been examined. However, the studied species featured a lifestyle, termed “tropical‐low abundance,” here not recognized previously for the genus; they occur in low abundances in tropical environments, they do not develop symbiotic associations with sessile invertebrates, and they are not conspicuously colored. Information on the sexual systems and lifestyles of more species needs to be examined before these observations can be placed into a comparative context within the genus.

The strontium content of roe collected from spawning brown troutSalmo truttaL. reflects recent otolith microchemistry

The relationship between the strontium content of the outer layers of otoliths (an indication of recent marine, estuarine or riverine habitat use) and the strontium content of roe in ripe female brown troutSalmo truttawas examined in fish collected from the Pomahaka River and the lower reaches of the Clutha River, South Island, New Zealand. A close relationship was found between the strontium content of roe and the outer layers of otoliths. This finding suggests that spawned eggs collected from redds could potentially be used to track the extent of upstream spawning migrations by anadromous brown trout.

Capelin migrations and climate change – a modelling analysis

The capelin is a small pelagic fish that performs long distance migrations. It is a key species in the Barents Sea ecosystem and its distribution is highly climate dependent. Here we use an individual based model to investigate consequences of global warming on capelin distribution and population dynamics. The model relies on input on physics and plankton from a biophysical ocean model, and the entire life cycle of capelin including spawning of eggs, larval drift and adult movement is simulated. Spawning day and adult movement strategies are adapted by a genetic algorithm. Spawning has to take place in designated near-shore spawning areas. The output generated by the model is capelin migration/distribution and population dynamics. We present simulations with present day climate and a future climate scenario. For the present climate the model evolves a spatial distribution resembling typical spatial dynamics of capelin with the coasts of Northern Norway and Murman as the main spawning areas. For the climate change simulation, the capelin is predicted to shift spawning eastwards and also utilize new spawning areas along Novaya Zemlya. There is also a shift in the adult distribution towards the north eastern part of the Barents Sea and earlier spawning associated with the warming.

Retinoid requirements in the reproduction of zebrafish

This study examines whether retinoids are essential in the reproduction of zebrafish. Using RT-PCR, it was shown that the ovaries and testes express enzymes that synthesize and metabolize the hormone retinoic acid (RA) ( raldh2 and cyp26a, respectively), and RA receptors ( raraa, rarga, rxrba, rxrbb, rxrga but not rxrab). Three new isoforms of rxrba were also observed in a variety of tissues. In other experiments, zebrafish were exposed for 11 d to diethylaminobenzaldehyde (DEAB), an inhibitor of RA synthesis, or fed a retinoid deficient diet for 130 d in order to evaluate the functional requirements of retinoids in reproduction. DEAB altered cyp26a transcript numbers in the gonads, suggesting an impact on RA, and decreased the number of spawned eggs by 95%. The retinoid deficient diet decreased whole body retinoids (retinol and retinal) by 68% in females and 33% in males. Females fed the retinoid deficient diet also produced 73% fewer eggs that contained 78% less retinal than controls. Fertilization rates were not affected. These studies have shown that the RA receptors are expressed in zebrafish gonads, and RA is required for the spawning of eggs. Dietary retinoid content influences reproduction, while retinyl ester storage levels appear to be of little significance. Females were more susceptible to retinoid perturbation than males, likely due to the cost of retinal deposition in the eggs. Overall, these studies have shown retinoids play a fundamental role in the reproduction of zebrafish, and the lack of retinyl ester stores in controls that successfully spawned illustrates that we have only a limited understanding of the retinoid physiology and requirements of fish.

Temperature-Dependent Regulation of Reproduction in the Diving Beetle Dytiscus sharpi (Coleoptera: Dytiscidae)

The effects of temperature on the mating behavior, gonad development, germ cell maturation, and egg spawning of the predaceous diving beetle Dytiscus sharpi (Coleoptera; Dytiscidae), were investigated. By field observations, we found that mating behavior started in October and occurred more frequently from November to December. Under our laboratory breeding conditions, we observed almost the same seasonal variation in mating behavior. We found that temperatures lower than 20 degrees C were required to trigger mating behavior. We also found the same temperature threshold triggered gonadogenesis as well as spermatogenesis. Furthermore, for females, exposure to lower temperatures (<8 degrees C) during the winter was required for egg maturation and spawning in spring; that is, there was a second threshold for successful female reproduction. We conclude that the termination of summer reproductive diapause of D. sharpi is regulated in a temperature-dependent manner, thus effecting the adaptation of D. sharpi to southern warm habitats.

GnRHa-induced spawning of wild-caught spotted rose snapper Lutjanus guttatus

The present study examined des-Gly10, [D-Ala6]-gonadotropin releasing hormone ethylamide (GnRHa) implant-induced spawning of recently caught wild spotted rose snapper (Lutjanus guttatus). The effect of implants containing 0 (control), 25, 50, 75 and 100 μg of GnRHa was assessed in ten females that had an oocyte diameter greater than 430 μm. All fish spawned except for the controls and one 100 μg implanted fish. The 75 μg implant-induced the spawning of eggs with a significantly higher percentage hatch (86.1±7.5 and 87.7±5.0%) and twice as many hatching eggs kg−1 body weight (BW). The 75 μg implant was used to induce the spawning of twelve females in two different tank sizes (700 and 1400 L) and with three different female:male densities (1:1, 1:3, 1:5). There appeared to be no significant effect of tank size or male density on egg quality or quantity. Non-linear 3D regressions for the dependent variables total number of eggs kg−1 BW, number of floating eggs kg−1 BW and number of hatching eggs kg−1 BW against the independent variables oocyte diameter (μm) and GnRHa dose (μg kg−1 BW) were significant (P<0.05) and had respective regression coefficients of r2=0.78, 0.80 and 0.85 (n=22). The models described a narrow range of GnRHa doses (240–280 μg kg−1 BW) and a broader range of oocyte diameters (440–500 μm) that predicted a spawn in excess of 100,000 eggs kg−1 BW. As a result, good quality eggs were obtained that enabled experimentation with larval culture.

Relation between broodstock number and spawning frequency and egg production of humpback grouper (Cromileptes altivelis)

&lt;p&gt;This study was performed to determine spawning frequency, number of ovulated egg and spawning time of humpback grouper (&lt;em&gt;Cromileptes altivelis&lt;/em&gt;) broodstock in hatchery. Broodstock of 20-83 fish in weight of 1.5-2.0 kg were reared in circular concrete tank 225 m&lt;sup&gt;3&lt;/sup&gt;. The results showed that increasing in number of broodstock increases spawning frequency (R&lt;sup&gt;2&lt;/sup&gt;= 0.694), and ovulated eggs number was also increased (R&lt;sup&gt;2&lt;/sup&gt;= 0.828). Spawning of humpback grouper can occur in the third to fourth week in every month.&lt;/p&gt; &lt;p&gt;Keywords: reproductive biology, spawning, &lt;em&gt;Cromileptes altivelis&lt;/em&gt;&lt;/p&gt; &lt;p&gt; &lt;/p&gt; &lt;p&gt;ABSTRAK&lt;/p&gt; &lt;h3&gt;Penelitian ini bertujuan untuk mengetahui frekuensi pemijahan, jumlah telur dan waktu pemijahan populasi induk ikan kerapu tikus (&lt;em&gt;Cromileptes &lt;/em&gt;altivelis) di hatchery. Jumlah induk yang bervariasi antara 20-83 ekor dengan ukuran 1,5-2 kg ditempatkan dalam bak beton bulat, kapasitas 225 m&lt;sup&gt;3&lt;/sup&gt;. Hasil penelitian ini menunjukkan bahwa dengan bertambahnya jumlah induk, maka frekuensi pemijahan yang diperoleh juga semakin meningkat (R&lt;sup&gt;2&lt;/sup&gt;=0,694), dan produksi telur juga semakin meningkat (R&lt;sup&gt;2&lt;/sup&gt;=0,828). Pemijahan kerapu tikus dapat berlangsung setiap bulan, di mana waktu pemijahan terjadi pada kuarter keempat hingga kuarter ketiga.&lt;/h3&gt; Kata kunci: Biologi reproduksi, Pemijahan, &lt;em&gt;Cromileptes altivelis&lt;/em&gt;