Control Of Aquatic Weeds And Undesirable Species From

Nursery PondSubmitted by,

Nazmul Ahmed Oli Reg: 12-05-2835Level: 3Course code: GFB-332

Nursery Pond A pond where fry & fingerlings are reared for 10 to 15 days for grow out.

Characteristics:• 10-25 decimal• 1-1.5m water depth• Rectangular pond with 1:2 or 1:1.5• Loam or clay loam soil• Organic matter in pond bottom should be below 10-

15cm• Pond dikes should be high enough, strong• Enough Light and air

Fig: Nursery pond

Types Of Aquatic Weed:

Aquatic plants can be divided into: (1) algae (2) rooted water plants. Generally rooted plants are 4 types:

Floating Weeds: Water hyacinth,

Lily

Emerged Weeds: Typha

Submerged Weeds: Hydrilla,

Marginal Weeds: Marsilea

Common Floating Plants

Spatterdock, Nuphar advenaWatershield

Submerged Plants:

hydr

illa

Problems of associate with Weeds Mortality Less primary productivity Successful competitor. Predator Shelter Hampering netting operation Fish flavor problems Pond water odor problems Stunned Growth of fish Disturbance in oxygen

Weed Control: Physical Removal

Drain

Dredge

Dragging

Raking

Cutting

Skimming

Harvesting

Aeration

Chemical Control Algae• Copper Sulfate, • Copper Complex (Cutrine)

Submerged Weeds• Diquat (Reward), • Fluridone (Sonar / Avast),• 2, 4-D, (Aqua-Kleen)• Endothal (Aquathol K)

Floating (Duckweed and Watermeal)• Diquat,• Fluridone

Emergent and floating Plants • Endothal, Fluridone, 2,4-D• Glyphosate (Rodeo)

Biological Control Herbivores can control by eating the weed..Eg: Grass carp

Aquatic weeds

Amount weeds

(kg/dec)

No. of grass

carp/dec

Weight of each

fish(g)

Time (day)

Hydrilla 275 2.6 113 42

Spyrodella 24 5 474 20

Fig: Grass carp

Undesired Species Control

Before stocking the fry in the nursery pond predatory & weed fish must be eradicated.

Common predatory fishes are: Channa spp., Clarias batraches, Heteropneustes fossailis, Pangsius,

Mystus sp. Ompok spp., Wallage attu Common weed fishes are: Puntius sp., Oxygaster sp., Ambassis sp., Amblypharyngodon mola.

Colisa sp., Rasbora sp

Removal of predatory and weed fishes:

Repeated netting. Dewatering the nursery pond. Drying. Use of poison. Use of pesticides.

Commonly used pesticides are:

Mahua oil cake• It kills fish at 200-250 ppm in 6-10 hours.

Tea seed cake• 145-150g/dec at 30cm water depth

Ammonia• Kills fish @ 20-25 ppm 

Rotenone• rotenone is 2 g/m3 for common predators and 8 g/m3 for eel.

Conclusion:

Nursery pond is very important for successful aquaculture. To get good quality of fry we should carefully manage the nursery pond. So we should always be careful & eradicate the weeds & predator or weed fish from the nursery pond.

Thanks

Everybody