Shellfish Breeding and Hatchery Management (2+1)

5.1.2 Identification of larvae and post-larvae of freshwater prawns

5.1.2 Identification of larvae and post-larvae of Macrobrachium rosenbergii

Macrobrachium rosenbergii has 11 larval and one post larval stage (i.e. 12 stages) in its life cycle. The larva passes through 11 zoea stages within a period of 23-35 days depending upon the temperature and availability of feed.

After these 11 zoeal stage, the post larvae stage is reached, which exhibits the features of adult prawn.

Key to the stages of larvae of Macrobrachium rosenbergii:

Stage	Prominent characters	Days after hatching	Size (mm)
I	Sessile eyes	1-2	2.0 – 2.1
II	Eyes stalked	2-4	2.2 - 2.4
III	Uropods appear	4-7	2.5-2.7
IV	Two dorsal epigastric teeth at base of rostrum	7-12	2.8-3.1
V	Telson narrower and elongated	11-16	3.2-3.4
VI	Pleopod buds appear	15-21	3.5-3.6
VII	Pleopod biramous and bare	18-24	3.7-4.2
VIII	Pleopods with setae	22-28	4.3-4.6
IX	Endopods of pleopods with appendices	25-31	4.7 – 5.2
X	3-4 dorsal teeth on rostrum	28-33	5.3 – 5.8
XI	Teeth on half of upper dorsal margin	31-35	5.8 – 6.2
XII (PL)	Teeth on upper and lower margin of rostrum; behavioural changes in swimming. They are generally transparent at this stage and have slightly brown coloured chromatophores on the head.