Astatheros nourissati pair in spawning dress Photo © Ole M . Ekeberg
Keijman in 1995 pointed out that this species did conform to the standards for the Amphilophus longimanus ( now Astatheros ) group ( although it is the most slender of the group ) and thus it was transferred to this genus . Recent taxonomy revisions has assigned them to the Astatheros complex , however , studies using a phylogenetic tree has found Astatheros nourissati firmly nestled within the Theraps complex . Should we instead go back to Allgayer original description and refer to the cichlid as Theraps nourissati ? As not to confuse , I will use currently accepted nomenclature and describe through the article as Astatheros . This is a medium sized fish with adult males attaining maybe as much as 25 cm , whilst females are a little smaller . A . nourisatti are characterized by a long fairly low body with strong caudal peduncle . The snout is long and the lips are large and fleshy . Unpaired fins are moderately extended with the dorsal and anal maybe reaching to the end of the caudal fin in mature males . The fish has a yellowish base colour with vertical black bars which sometimes show as a large spots especially on the middle flank of the fish . A black mark is found behind the pectoral fins and a gorgeous triangle shaped wine red flush colours the fish from behind the gill plate to behind the ventral fin . The head is yellow and the throat exhibits a copperblue colour as does the eye . All in all there is a strong resemblance to Astatheros robertsoni although A . nourissati is less blue in colour . A . robertsoni should be considered as the sister species to A . nourisatti and their range is overlapping but they have yet to be found living symaptrically . A less similar species is Astatheros rostratus which although similar in colour , it has a much longer snout it is also only found in Nicaragua a country from which A . nourisatti is absent . Astatheros nourissati is very much a rheophilic cichlid which is found in rivers of medium to strong flow although it is reported to prefer stiller areas of water within these flows , this again sets it apart from other species of the Theraps genus which very much prefer and are strongly adapted to cope with fast flowing water . The water of the habitat of this fish is always alkaline and varied from hard to very hard . This has to be remembered in captivity where acidic or soft water could do untold damage to this fish in the long term . A large tank is a must for this species , 1.5 meters being the smallest length which should be considered . Although shy in nature swimming space is appreciated and a large volume of water also gives more leeway should any pollution or water mismanagement occur .
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