Shellfish Breeding and Hatchery Management (2+1)

23.1.2 Preferred water quality parameters for shellfishes

23.1.2 Shellfishes and their environment

Management of the tank water has become more inevitable in the case of all aquatic organisms. The confined environment makes the shellfishes to suffer if the water quality is bad and the parameters are not at preferred level. It exerts much pressure on the brooders and also larvae.

The following can be considered as the general recommendation for the good water in hatcheries.

S.N	Parameter	Fish Hatcheries	Shellfish hatcheries
1.	Alkalinity	10 – 400	75 – 150
2.	Total Hardnes (ppm of CaCO3)	10 – 400	20 – 80
3.	Ammonia (ppm)	<0.02	<0.001
4.	Ammonia (Total Ammonia Nitrogen)	<1.0	<0.01
5.	Calcium (ppm)	4 – 160	20 – 80
6.	Dissolved oxygen (ppm)	3 - Saturation	4 to Saturation
7.	Carbon dioxide (ppm)	0 – 10	0 –1
8.	Chlorine (ml/l)	<0.003	<0.001
9.	Hydrogen sulphide (ppm)	<0.003	<0.001
10.	pH	6.5 – 8	7.5 – 8.0
11.	Total Dissolved solids (TDS) (ppm)	< 400	< 200
12.	Total suspended solids (TSS) (ppm)	< 80	< 20
13.	Micro elements (Zn, Cd, Se, Fe, Mn, Cu, Ni, Cr.) (ppm)	< 0.01	< 0.01
14.	Macro elements (Na, K, Kg, S, etc)	< 1.0	< 1.0
15.	Turbidity (Light penetration depth)	30 – 50 cm	30 – 80 cm

There are many minor components in the water other than the items listed above, which can also influence the shellfishes. However, managing the above parameters will control all the other quality parameters in the culture water.

The following table shows the effect of major water quality parameters on the crustaceans:

S. No.	Nature of the parameter	Influence on the organism	Nature of the effect (negative)
1.	Dissolved oxygen super saturation	- Gas bubbles will be trapped in the eye, gills, etc..	May be lethal
	Low concentration 3ppm	- System will become anaerobic in the bottom: Decomposition will result is the production of unwanted gaser.	Fishers will be affected badly
		Nitrification process will be stripped
2.	Carbon di oxide	pH Variation in water will	Lethal
	High concentration	affect the fish growth
	> 5ppm	Will alter the alkalinity, so that the fish growth will be reduced
3.	High Minerals High Handers	Osmorgulation will be affected laner conversion of feed to flesh	Lethal
		Calcification on the body surface. Skin diseases - growth of unwanted organism in the tank
4.	High or low pH	Affects the growth. Lead to death of the fish	Lethal