Etroplus canarensis

Introduction

Etroplus canarensis is a small sized fish in the genus, it has a TL(Total length) of 4.6 ".
It is found in Karnataka, South India.

Taxonomy

(Click for details of Cichlid taxonomy)

Etroplus canarensis was first described by Francis Day in 1877.
The genus name is derived from the words 'etron' meaning belly and 'oplon' for arms.
This refers to the spines that are present on the anal fin, i.e the long spinous anal-fin.
The species name is derived from the state of Canara (Karnataka) which is habitat of this fish.

Description

Shape :-

• Body is deep and compressed, depth of body is 53 % of SL (Standard length).
• Eyes are large and placed laterally, eye diameter is 11.2 % of SL (standard length) .
• Mouth is small and terminal .
• Teeth are small and fine (villiform) and found in two or three rows in jaw. There are no teeth on palate (roof of mouth).

Fins:-

• Dorsal fin is inserted above pectoral fin base, with 21-22 spines and 8 soft rays.
  The spinous base is longer than soft rayed base.
  Dorsal fin spines increase in length till fifth spine, behind which they continue about equal.
  Soft Dorsal fin is pointed.
  
• Anal fin has 16 spines and 6-7 soft rays.
  Soft Anal fin is pointed.
• Pelvic fins are located on thorax and have 16 rays.
• Caudal fin is concavely curved but not forked (emarginate).

Scales and lateral Line:-

Scales are weakly ctenoid and are of moderate size, they extend to the base of soft dorsal and anal fins.
There are 30-31 scales in longitudinal series.
Lateral line is interrupted as in all cichlids and it ceases after 15-25 scales or continues as small pored holes.
Lateral line contains 15 -25 scales, the upper lateral line is seperated by 5 scales rows from dorsal fin base, and lower lateral line is separated by 16 scales from pelvic fin base.

Remarkable feature:-

A remarkable features of this family, is the development of the front part of the gas bladder and corresponding changes to the posterior of the neurocranium(back part of the skull that houses the brain) to create a direct connection between the gas bladder and inner ear .
This feature is not seen in any other Cichlid families.
This allows fish of this genus to have remarkable hearing power.

Distribution & Habitat

Etroplus canarensis is endemic to Western Ghats in India and known to occur in Kumaradhara and Nethravati Rivers in Karnataka India.
Western Ghats has been designated as one of the 19 Bio- Diversity hot spots in the world by UN.
It was thought to be found in Kumaradhara rivers system for a long time however it was discovered in Nethravati river also.

Etroplus canarensis is a fresh water fish unlike other members of its genus.
It occurs in oxygen soft freshwater in both rivers.
In nethravati river it is found 50 km from sea, other species of Etroplus are found downstream.
One spot in nethravati river had clear water flowing over rocky substrate during dry season.
Water parameter reading at this area are 6.5 ph,Gh 2 dh,Kh 2 dh, TDS 50 ppm.
In the Kumaradhara basin it was recorded at a spot where pH was 6.5, tds 40 ppm, conductivity 85 µS, GH 2.0 and KH 2.0 with a temperature of 33.1.
These habitats are highly seasonal in nature and during monsoon they get flooded with large amount is water which is turgid and fast flowing.

Diet

Etroplus canarensis is omnivorous and has been seen grazing on aufwuchs (hard algae that grows on rocks) in the wild.
Hence a varied diet with algae is recommended.
They love to eat plants however like other cichlids they do not dig.

Conservation Status & Threats

Etroplus canarensis is listed as “Endangered” in “The IUCN Red list of Threatened Species” 2013.2.
Etroplus canarensis has been assessed as Endangered because of its restricted distribution to two locations, with an extent of occurrence (EOO) of less than 5,000 km and an area of occupancy (AOO) of less than 500 km.
There is also an going decline in habitat quality as a result of pollution and sand mining, and the threat of over-collection for the pet trade.
Population of Etroplus canarensis is listed as stable by IUCN.

Major Threats: One of the major threats to E. canarensis is the unmanaged collection for the aquarium hobby.
Since the populations are restricted to two locations, indiscriminate collections can possibly wipe out the species.
However, with the increase in availability of captive bred fish from Indonesia, pressure on wild collection seems to have declined.
Additional threats include both intentional and unintentional harvest as a food fish, pollution from agricultural and domestic sewage, and habitat alteration due to sand mining.
In 1996 many fish in the Kumaradhara River died from pesticide poisoning .
The habitat in the Kumaradhara is in reasonably good shape, with very little human impact.

Conservation Actions: Bisle Ghat in River Kumaradhara should be preserved as an important habitat for the species.
Measures such as no-take zones and freshwater sanctuaries, as well as captive breeding for stock enhancement are also recommended.

Tank Size and setup:

A tank of about 200 liters can be set up for these cichlids.
The tank setup should imitate a river flowing stream or river bed, with gravel of multiple size, small rounded boulders, driftwood can be added to simulate roots of trees.

It should be noted that Etroplus canarensis are not brackish water fish, they are found in oxygen rich freshwater.
In nature they are found in soft water with Gh= 2-4 and Kh = 2.
Very good filteration is required to keep nitrates very low and good oxygenation in water.

Tank Mates:

Etroplus canarensis form loose groups in wild when they are young, however they tend to become solitary as they grow up.
A minimum group of 6-8 is recommended, in smaller groups the weaker specimens will be picked upon.
A dominancy hierarchy will be established by the time they reach maturity.
Other tank mates can be cyprinids like Dawkinsia spp., Devario malabaricus or Rasbora daniconius.
They are not aggressive cichlid so should not be kept with other fish or cichlids which are aggressive in nature.

Breeding:

There are no obvious external sex differences in fin length or intensity of colour pattern.
Adult males are larger and heavier.

Etroplus canarensis is a bi parental substrate spawner, however they are not monogamous, i.e a permanent pairing does not take place. Weak temporary bonds are formed during mating and brood care.
Observation in wild have seen them moving in pairs even when not breeding, however it is not clear if these pairing is for life.
Their natural habitats are prone to heavy flooding during monsoon season, hence the fish breeds in months between December and April.
At this time the water levels recede and temperature drops.
These conditions can be replicated in aquarium to simulate breeding.
Daily water changes of about 20-25 % can be done to replicate the drop in temperature.
When fish is ready for breeding the colour pattern changes, the dark vertical body bars are replaced by solid dark bars and vertical bars appear on front of head.
A breeding site is selected and surrounding area is defended against intruders.
Eggs are normally deposited in a sheltered position on the side or top of rock and are attached by short filaments.
The eggs are defended by both parents, however the male can breed with other females if they are ready to breed. Eggs hatch after 4 days at temperature of about 26 C, fry are free swimming in further 2-3 days.
Eggs can also be removed after they are deposited, as the parents or other fish can eat them. if this is done the rock with eggs should be removed, water from parents tank should be used.
Water flow across eggs can be simulated by using a air line close to rock.
Once fry are free swimming they can be fed armetia.