|
PEARLFISH
PRESS
Back
to top
|
Killifishes 1999
Sample texts:
Rivulus punctatus Boulenger,
1895. Male, c. 1 1/2 inches
TL; presumptively wild specimen from an Argentine locality, via
wholesale aquarium trade, 1986.
Boll. Mus. Zool. Anat. Comp., 10(196):1-3.
Family: Rivulidae
The Paraguay, lower Parana, and Uruguay Basins in Brazil, Bolivia,
Paraguay, and Argentina; in the Rio Guapore Basin, Brazil (Costa,
1995). Huber (1992) additionally cites records from near Porto
Allegre, Rio Grande do Sul, Brazil, and states that the species
probably exists in Uruguay as well.
To 1 3/4 inches.
Rivulus punctatus is a small, very variable species over
its extensive range that Huber (1992) claims may be a single
polytypic species or may encompass several cryptic species, and
that defines the southerly limit for the genus. Costa (1995)
recognized six species in the R. punctatus species-complex,
including modestus, zygonectes, pictus,
violaceus, and decoratus, providing a key and extensive
comparative data. He considers the group so defined to be monophyletic,
in contradistinction to the larger group proposed by Huber (1992).
This species has been misidentified as R. strigatus (a
member of the closely related R. geayi complex, if not
a synonym of R. geayi) and also represents the fish known
as Rivulus NSC-11 in the early 1970s.
R. punctatus is undemanding and easily maintained, reportedly
tolerant of poor water quality, low dissolved oxygen levels,
and temperatures in excess of 100 F. Propagation is characterized
as "uneasy" by Huber (1992), but relatively easy by
most other authors (see especially Collier & Stiernberg,
1974; Mecca, 1977; Stoops & Castro, 1989, and; Phillips,
1989). Eggs are deposited in mops, vegetation, and/or gravel,
and incubation times range from 10 to 18 days at temperatures
from 68 F to 82 F. Breeding set-ups may accommodate a single
pair of fish or a larger breeding group. J.P. van Ess (cited
in Fromm, 1986) reported captive specimens' preference for "polluted"
water, stating that the fish will not spawn in nitrite-free water.
This claim is not inconsistent with wild specimens' reputed preference
for shallow, often stagnant bodies of water. All authors report
the species to be slow growing, no doubt due to its meager feeding
habits.
Collier, G. and L. Stiernberg. 1974. Identification, care and
breeding of Rivulus punctatus (NSC-11). J. Amer. Killifish
Assoc., Oct, 7(10):349-355.
Costa, Wilson J.M.E. 1995. Revision of the Rivulus punctatus
species-complex (Cyprinodontiformes:Rivulidae). Ichthyol. Explor.
Freshwaters, Oct, 6(3):207-226.
Fromm, Dan. 1986. Rivulus as live animals. J. Amer. Killifish
Assoc., Jan/Feb, 19(1):4-53.
Huber, J.H. 1992. Review of Rivulus -- ecobiogeography
-- relationships. Societe Francaise d'Ichtyologie, Paris.
Mecca, Ray. 1977. Rivulus: An introduction to the genus.
J. Amer. Killifish Assoc., Nov/Dec, 10(10):264-270.
Phillips, Jack. 1989. Rivulus punctatus. J. Amer. Killifish
Assoc., Nov/Dec, 22(6):200-201.
Stoops, Ken and Alfred D. Castro. 1989. Rivulus punctatus,
Boulenger 1895. Amer. Killifish Assoc. Index. 2pp. (Color
photo by Ronald de Boor.)
Pantanodon podoxys Myers, 1955.
Male, c. 3/4 inch TL; aquarium material, derived from stock collected
by Brian Watters (Canada), Ruud Wildekamp (Netherlands), and
Ian Sainthouse (England), June 14, 1995, 9 kilometers north of
the town of Tanga, northeastern Tanzania ("Tanga TAN 95/15").
Trop. Fish Mag., March, 4(4):7.
Family: Poeciliidae
Coastal regions of Tanzania and Kenya, East Africa; in fresh,
brackish, and marine waters.
To 1 3/4 inches.
Until recently, Pantanodon podoxys has been a very obscure
fish even to killifish specialists. Turner (1966) reported only
3 collections comprising a total of 8 specimens prior to his
1963 importation of 8 living specimens (from a larger collection
by J.H.E. Leakey in a stagnant freshwater pond 12.5 kilometers
north of Tanga, Tanzania). The diverse biotypical parameters
from various collections are given in Turner's 1966 article and
in a follow-up article in 1983, and comprise freshwater, brackish,
and marine habitats. Watters (personal communication) described
the 1995 Tanga habitat as "a small pool fed by a small estuarine
stream at the head of extensive tidal flats with mangrove swamps,"
containing "brackish" water (exact salinity not quantified),
with total dissolved solids in excess of 2000ppm. Most aquarists
report using "brackish" water for this species (presumably
25% to 50% sea water; Watters suggests 50%), although the present
author utilizes water that is essentially fresh (<1 quart
sea water per 10 gallon aquarium) without apparent adverse effect
on overall health, fecundity, or viability of the eggs.
Whitehead (1962) speculated that the absence of jaw teeth and
possible trophic adaptations of the gill rakers in P. podoxys
indicate that the species is a filter-feeder. Turner (1966 and
1983) pointed out that, anatomy notwithstanding, P. podoxys
is not an obligate filter-feeder, since his specimens
accepted foods such as Tubifex worms and small Daphnia.
The present author's specimens have likewise exhibited excellent
health and reproductive vigor on an exclusive diet of not-very-finely
crushed flake foods and adult brine shrimp, although the latter
are taken only with considerable effort on the fish's part. Eggs
are deposited throughout floating mops (rarely in sunken mops)
and hatch in 8 to 21 days at 68 F to 80 F. The fry are very small
upon hatching, and must be started on correspondingly small living
foods or finely powdered and/or liquid prepared foods. Duzen
(1997) reports newly hatched fry to take brine shrimp nauplii,
speculating that they are able to do so only by first tearing
the shrimp to pieces.
The genus contains only one other species, the Madagascan P.
madagascariensis, originally described in the genus Oryzias,
which, in interesting contradistinction to P. podoxys,
possesses jaw teeth. Parenti (1981) placed Pantanodon
and related Old World lampeye genera in the otherwise New World
livebearing family Poeciliidae, while not recognizing the subfamily
Pantanodontinae erected by Myers (1955). Turner (1983) provided
interesting commentary on the taxonomy and biogeography of the
genus. Most recently, Seegers (1997) reported on his placement
of podoxys into the synonymy of Aplocheilichthys stuhlmani,
although he retains the species in the genus Pantanodon.
The name podoxys is used here pending publication of the
Killifish Master Index, Fourth Edition (Lazara, in press).
Parenti, Lynne R. 1981. A phylogenetic and biogeographic analysis
of cyprinodontiform fishes (TELEOSTEI, ATHERINOMORPHA). Bull.
Amer. Mus. Nat. Hist.,168(Art. 4):335-557.
Seegers, Lothar. 1997. Killifishes of the world: Old World killis
I. A.C.S (Aqualog). Morfelden-Walldorf, Germany. 160pp.
Turner, Bruce J. 1966. A new record and preliminary observations
of the teleost Pantanodon podoxys Myers (Atheriniformes:Cyprinodontidae).
J. Amer. Killifish Assoc., Summer, 3(2):31-32.
Turner, Bruce J. 1983. Pantanodon: A personal memoir.
J. Amer. Killifish Assoc., Sep/Oct, 16(5):188-194.
Whitehead, P.J.P. 1962. The Pantanodontinae, edentulous toothcarps
from East Africa. Bull. Brit. Mus. Nat. Hist., 9(3):103-137.
|