As per as physiographical condition and fisheries is concerned, the State is broadly divided into three distinct zones:

1. The lower Altitude (Tropical Zone, extends upto 300 meter above msl) covering 10% of the area

2. The middle Altitude (Sub-tropical zone, extends between 300 – 1200 meter msl) covering 70% of area

3. High Altitude (Alpine Zone extending beyond 1200 meter msl) covering 20% of the state’s total area.

The State has potential network of natural resources in the form of lentic and lotic water bodies viz: rivers, streams, lakes, ponds, beels etc.The climatic variation due to increase in altitudes from foothills belt to Alpine zone, provides different fish species available in different habitat. The hot and humid foothills belt are home to warm and semi-warm water fish species like Indian Major Carps, exotic carps, Cat fishes, etc.The middle belt with gradient upto 1200m (msl) which progressively become cold with less humid and moderate rainfall provides maximum resources of both cold and warm water fisheries. In the higher altitude zone with cold and extreme cold belt, harbors snow trouts, Garras, Noemacheilus, Glyptothorax and occasionally the lesser barils.

The exotic trout fish viz - brown and Rainbow species have also been introduced in the this belt by the department of fisheries during early 1960’s to 1980’s which is thriving well in rivers and lakes of Tawang, Mechuka and West Kameng districts at present.

Fish Bio-Diversity

The State is home to more than 250 fish species as recorded by various research Institutes/Scholars which have food as well as ornamental values.The principal fish species which supports the river system of the State are:

1. Mahseers( Tor tor, Tor Putitora, N. hexagonolepis,) Golden Mahseer (Tor putitora)

2. Snow trouts (Schizothorax Richard sonii, Schizopyge progastus, s. esocinus )

3. Carps ( labeo dero, labeo pangusia, semiplotus semiplotus, chagunius chagunius)

4. Lesser barils ( Barilius bendelisis, Barilus bola , Barilus tileo, Barilius barana)

5. Cat Fishes (Mystus spp, Ompok spp, Bagarius bagarius, Glyptothorax spp., Clarius Spp)

6. Minnows (A. mola, Danio Spp., Puntius Spp.)

7. Loaches (Botia Spp., lepidocephalus spp., Noemacheilus Spp.)

8. Misc. spp. (Garra spp., Aspidoparia Spp., Badis badis, Wallago attu & fresh water prawns)

The GOLDEN MAHSEER (Tor putitora) has been declared as STATE FISH during the FY:2010-11.

The Fisheries resources are as below

Resources Utilized for Fisheries development