Alloophorus robustus

Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Alloophorus robustus
Original Description: 

  BEAN, T. H. (1892): Notes on Fishes collected in Mexico by Professor Dugès, with Description of new Species. Proceedings of the United States National Museum. No 15: pp 283-287

Etymology: 

  The name comes from the Latin and means "strong". Bean didn't explain why he had chosen that name, but compared with other representatives of the genus Fundulus, wherein Bean placed this fish, he is stronger and bigger, so maybe that might have been the reason. Another, more probable option, would be the strong jaws, typically for this species, that inspired Bean to this species name.

Holotype: 

  Collection-number: United States National Museum, Cat. No. USNM-43760.

  The Holotype is an adult female of 107mm standard length, collected by A. Dugès. He sent two specimen to the Museum on 24.08.1891.

English Name: 
Bulldog Goodeid
Mexican Name: 
Chegua
Synonyms: 

Fundulus robustus Bean, 1892

Fundulus parvipinnis   Garman, 1895

Zoogoneticus robustus   Meek, 1902

Zoogoneticus maculatus   Regan, 1904

Karyotype: 

  The Karyotype describes the number and appearance of chromosomes during the phase of condensation, classified by the position of the centromere (Levan et al., 1964).

The following abbreviations are employed:

 

M = large metacentric chromsome (a result of Robertsonian fusion)

m = small metacentric chromsome (centromere at medium position)

sm = submetacentric chromsome (centromere at submedian position)

smst = submetacentric-subtelocentric chromosome (continous series)

st = subtelocentric chromosome (centromere at subterminal region)

stt = subtelocentric-acrocentric chromosome (continous series)

t = acrocentric chromosome (centromere at terminal region)

 

The Karyotype of Alloophorus robustus, following Uyeno, Miller & Fitzsimons, 1983:

2n = 30    18M / 2m/ 10stt  

Size: 
The maximum known SL is 143mm (Miller et al, 2005).
Terra typica: 

  The Holotype comes - following Bean - from "Mexico". He described several other species from the collection of Dugès from 1891, all of them collected in the state of Guanajuato, so probably Alloophorus robustus had been collected there, too. On the Holotype is a sign attached with "Patzcuaro, Mex."

Status after IUCN: 

  not assessed

Status following other sources: 

  Status: Vulnerable

  Population development: Some decline since 2000 

Distribution and ESU's: 

  This species comes from the Pacific Slope and can be found in several drainages. It has been reported from the Río Lerma basin, including lagos de Chapala, Yuriria, Cuitzeo, Patzcuaro and Zirahuén. Other localities are the Presa de San Juanico and northwestern tributaries of the Río Balsas in Michoacán. It is widly distributed but not very common.

 

  ESU ist short for Evolutionarily Significant Unit.  Each unit expresses an isolated population with different genetic characteristics within one species.  ESU's can be defined by Molecular genetics, Morphology and/or Zoogeography and help in indicating different phylogenetic lineages within a species. The abbreviation for an ESU is composed of three letters of the genus, followed by the first two letters of the species name and an ongoing number in each species.

 

  In Alloophorus robustus, actually four ESU's are being distinguished. The first one (Alpro1) is in use for specimens from the Lago de Chapala and connected rivers like the lower Río Lerma, the Río Duero with the famous springs of La Luz and Orandino, the lakes of Los Negritos and watersheds southeast of Chapala like the region of Cotija, the Presa de San Juanico, the bath at Tocumbo and the spring system at Uruapán. This ESU quite sure comprises a separate to be described species.

  Alpro2 encompasses populations from the Lago de Cuitzeo and Zacapu basins, Alpro3 those north of the middle Río Lerma (Río Turbio, Río Guanajuato, Río Laja). The fourth and last ESU, Alpro4, is in use for fish from the type location (Lago de Pátzcuaro) and connected waterbodies and from the Lago de Zirahuén.

Habitat: 

  Alloophorus robustus inhabits typically quiet waterbodies like lakes, ponds, reservoirs and slowly flowing rivers and streams. It lives over substrates of mud, sand, clay and rocks in depths of 1 to 2m. Different forms of vegetation can be fond, including water hyacinths (Eichhornia), water lilies (Nymphaea), Scirpus, Ceratophyllum, Potamogeton and green algae, but may be sparse. Brian Kabbes described in 1998 one habitat of this species, the Lago Orandino. He recorded a clear lake with a bit turbidity. Under overhanging plants, he saw Alloophorus waiting for prey. He predicated the species as shy, apparently preferring some current.

Colouration: 

  This species shows many big blotches on its sides (extending onto belly in juveniles), that are fading in large fish. Breeding males show rarely a subterminal black band and a yellow terminal band in its median fins. Bean designated the colour as uniform pale brown with unspotted fins and the opercle with a golden tint. Wischnath meant, " according to the mood the body appears, besides gray brown, more or less dark, including the fins. In a few cases the body exhibits a dark, weakly marked spotting." However, young specimen remind of a Chapalichthys with bigger and rounder spots, covering the sides.

Biology: 

  Meek found (in May 1904) 108-120mm long females containing 20-38 young, each 17-19mm long. Young 20-22mm SL in UMMZ collections appeared between 12 May and 12 June. A 19mm fish had been collected on 19 February in a warm (24.5°C) spring and another one of that length was captured on 9 March from Lago de Camécuaro near Zamora. Thus there is the potential for an extended reproductive period. Ovaries with embryos in various stages of development were noted between 5 may and 16 August from Lago de Patzcuaro, but young were born only during a two-month period (April - June, Mendoza, 1962). This suggests there is only one brood cycle. The average of brood size has been 23.7 young per ovary, including only 0.42% runts.

Diet: 

  This species has got a large mouth and strong jaws. The teeth are sharply conic and it’s got a relatively short intestine. This fish is probably the most highly developed carnivore in the family feeding mainly from other fish, big insects and worms. Alloophorus robustus is definitely a predator. Brian Kabbes characterized the way to hunt like that of a pike.

 

In the gut of one Alloophorus had been found a middle-sized Poeciliopsis infans.

Remarks: 

  Alloophorus robustus might be the largest Goodeid besides Goodea atripinnis, reaching - following some authors (eg. Meek)- maybe 170mm. Like many other predatory fish, live food - mainly fish, crayfish, big insects and worms - seem to be necessary for breeding in captivity.

 

  Riehl (pers. comm. to Hieronimus) documented a phenotypical female of 150mm SL with testes and first beginnings of a splitfin.

 

  Last phylogenetical studies (Domínguez, pers.comm. 2011) revealed two lineages within Alloophorus, with a distant population from the Lago de Cuitzeo basin that might present a different species.

 

  The Bulldog Splitfin disappeared from a huge part of its distribution range, including the Lago de Chapala, the Río Lerma and Santiago and the Lago de Zirahuén basin. A reason therfore - besides desiccation and pollution - seems to be the introduced Largemouth bass (Micropterus salmoides), being a bigger and stronger predator than Alloophorus robustus. In addition to this, the species is used for human consumption and may be overfished locally.

 

  The closest relative of the genus Alloophorus seems to be the genus Chapalichthys.

Husbandry: 

 

Attention: This are not the correct husbandry guidelines for this species, it is just a working template that needs to be adapted!!!

  

  Looking on the biotopes of Allodontichthys hubbsi, they suggest the species may prefer a habitat with moderate to swift current, structured with gravel, rocks and boulders. Most breeders observed a high level of aggression between the adult fish, so the tank set up should prevent the fish from seeing each other most of the time. Fry is eaten in most of the cases, but it may depend on the quantity and quality of food and on the number of space to hide. When several different stages of juveniles occur, fry may be neglected, so it makes sense to add separate brought up fry to the group with a size of 1.5 or 2cm to provide these stages and get a flock breeding colony. Unfortunately, it was not able until now to breed bigger colonies so this statement is made from the comparison with related species and the personal comments of successful breeders.

 

 The recommended tank size is at least 150 liters, bigger ones with a generous base and little height (25cm are enough) are better for sure. With rocks well structured tanks combined with some roots and/ or wood seem to do best with this species. The current should be moderate or swift. 

 

 In the wild, the species seem to feed from small or middle - sized invertebrates like bloodworms or insect larvae, so feeding with similar food, Daphnia, Mysis and other food from animalistic sources will be best for this predatory fish.   

 

 Concerning water quality, this species is in need of greater water changes (60 - 80% every week) like most of the Goodeids, especially river inhabiting species, so an automatic water changing system can be helpful. Otherwise, in combination with constant temperatures higher than 24°C, fish may get sick, lose resistance against diseases and age too fast. So for keeping the strain healthy and strong, give the fish a rest during winter time with temperatures lower than 20°C for 2 or 3 months so they stop producing fry. In spring, when the temperature slowly increases, they will start spawning at 20 or 21°C and won't stop until it gets colder again or when it gets too warm (25°C?).

 

 This species may do very well when is kept in the open from spring to fall, starting when the temperature exceeds 15°C water temperature and cold periods are no longer expected. During the warm summer, reproduction will stop and may occur again in fall. Bring the fish in before the temperature goes below 10°C water temperature and keep them cool for the first days, then slowly raise the temperature but try to stay below 20°C over the winter time.