How to obtain proper and sufficient fish-fry and juvenile prawns used for stock-ing in blackish-water pisciculture in the province of Kwangtung, China, is a keyproblem in pisciculture. To solve these problems it is necessary primarily to knowthe exact time, the maximum number and species components of fish-fry and juveni-le prawns entering the pond in the year. Steps are therefore taken to make quanti-tative investigations in two ponds of embanked sea-water at Changsha-wan of Hai-fong district in Kwangtung from March of 1960 to March of 1961 and from Aprilof 1962 to May of 1963, and the result of the investigation is given as followings. A hemp-twine net of oblong shape was used to collect the samples. Its mouth is 1.8m×1. 38m and its length, 11 m., Its mesh in anterior portion is 2.8 cm and in posteri-or portion, 0.5 cm. The sluice of each pond was equipped with one such net to workone to four hours for each day during the flood-tide period, only the first hourcollection was taken as sample. When the sluice was opened, the sea water carry-ing with itself the fish-fry and juvenile prawns, rushed into the pond. Average mon-thly quantitative catches of fish-fry and juvenile prawns made by the net were com-puted for comparison. 71 species of fishes attributed to 33 families and 7 species of prawns were col-lected in ponds, their names were listed, and there were 4 species of mullets, 15species of miscellaneous fishes, and 6 species of prawns as predominant fry and ju-venile forms. The time of presence and entering of fish-fry and juvenile prawns in the pondswas found in different periods of the year for each species or groups. Among mul-lets: Mugil cephalus, January-April, highest frequency found in February (69.2-71.4%); Liza dussumieri, September-February, highest frequency found in Decemb- er (82.4-100 %); Liza Carinatus, February-June, highest frequency found in Ap-ril (92.3%) or March (100%); Mugil sp., September-December, (82-100%).Among Prawns: Penaeus merguiensis, May-February, highest frequency in July-November (80-100 % ); Metapenaeus joyneri, June-December, high frequencyin June, September and November (100 %); Metapenaeus monoceros and Acetesjaponicus, nearly all year with high frequency. Miscellaneous fishes consisted chieflyof Gobiidae, Tetradontidae and Sparidae. According to fry collections made fromMarch to Aprii, 1960, Gobiidae formed (43.9%). Tetradontidae formed (49.9%) andSparidae formed (2.5 %) of the total miscellaneous fishes entering the ponds.Theyappeared in major parts of year with in continually high frequency. The seasonal variations in components of fish-fry and juvenile prawns werevery marked. Mullets formed the dominant group in winter of 1961, but were repla-ced by miscellaneous fishes in winter of 1963. Miscellaneous fishes formed thedominant group in spring of 1960, but were replaced by Mullets in 1962. Theremaining half year was dominated by prawns, of which Acetes japonicus consistedchiefly of adult individual played the leading role. The authors have used the indexof diversity of Magaref to demonstrate status of the species component of fish-fryand juvenile prawns. Assuming the total number of species taken by month as a com-munty, the following values of indices were obtained, smallest value: 1.45 (Febru-ary, 1961) and 2. 07 (April, 1962); largest value: 3.80 (June, 1960) and 3. 86(August, 1962).It indicated that the dominancy of species composition would be observedin February or April, whereas the reverse situation would observed in June or August.The heterogeneity index of Motomura was also used. The maximum value of thisindex was found corresponding with the minimum value of diversity index. The total catches of fry and juvenile prawns were found to be minimal in win-ter, increased in spring, then attained maximal in summer, and decreased in autu-mn.The patterns of curves for the two observation years do not seem to coincide en-tirely. In 1960, the fry of mullets increased gradually in numbers from January toApril, decreased in the following month,with an another new peak in October.