Phalloceros caudimaculatus (Hensel, 1868)
little livebearer was the first fish that I kept other than goldfish. In 1954, a friend and I caught a few specimens from a pond in the
grounds of the local Doctor's residence, in Kent Town. Along with the goldfish and
the aquatic Cassula species that I grew in an old concrete pond,
Leopardfish began my adventure in aquaculture. They were raised in a
well-planted, old, glass, battery-case and thrived - outdoors. The water reached
daily temperatures over
35oC in the summer and dropped appreciably at night. The winter minimum temperature was near 4oC. A few
fish always survived winter and numbers grew quickly each
They took crushed food granules and thrived on algae, constantly
mouthing the algal coat on the walls of the case. They eventually
ended up in the pond and, like the goldfish, became food for
marauding gulls. For
sentimental reasons, I would like to keep some again but,
unfortunately, this species has become a feral nuisance in parts of
Australia and it is not sold in many Pet Shops. Phalloceros caudimaculatus has
to dams and creeks as a mosquito control species (a role for which
this species is unsuited) or by people
releasing their former pets into the waterways.
pair; female above, male below. Note the long
gonopodium on the male and the deeper body of the female.
ABOUT THIS SPECIES
Leopardfish or Speckled Caudy,
Phalloceros caudimaculatus (Hensel
1868), is a tiny, pelagic, non-migratory,
livebearer (family Poeciliidae) and is similar in size and shape to
the related Gambusia holbrooki, the Plague Minnow or
Mosquitofish, but differs in colour and patterning. The body colour
is silver, often tinted in yellow, and the males are distinctively
speckled with irregular, black spots and blotches. Females are
less conspicuously spotted than the males and are much larger, growing to
4 cm and males to 2.5 cm in length. They are native to eastern South
America between Brazil and Uruguay, in tropical streams, estuaries
and still ponds with dense aquatic vegetation. In their
tropical, native homes the water temperature
ranges 20°C – 24°C. Water conditions vary widely, from freshwater to
brackish, with pH range: 7.0 – 8.0 and dH range: 9 - 19.
hardy and tolerate a wide range of environmental conditions. They
mainly eat plant material and sediment, extracting the
micro-organisms that live there. Contrary to popular belief, they do
not consume a substantial number of mosquito larvae and have little
value in mosquito control. In South Australia, the River Murray
fluviatilis) is best used to control mosquitoes in dams.
Leopardfish are typical livebearers, giving birth to live young
in broods of up to 80-100 offspring. That makes them prolific if
conditions are right and a rapidly breeding pest species in our
Leopardfish can be an interesting aquarium subject if care is
given to prevent release them into Australian waters. They are easy to
keep and breed, can be kept in unheated aquaria (indoors) and
adapt to a wide range of water conditions. They are best kept in a
tank with a fine, gravel substrate and well-planted with
Vallesnaria sp. and other aquatic plants,
with some surface plant cover and with slow water movement.
The water conditions are best if kept at 20°C – 22°C, pH 7.4 - 7.6,
in hard water to which a little salt (sodium chloride) has been
I have not kept these fish with other species and, unless they
are fin-nippers, I think that they would be safe with fishes of a
similar size such as Rice Fish, Zebra Danios or White Cloud Minnows
in an unheated, indoor aquarium or with other livebearers in a
tropical aquarium. They are active fish and forage by mouthing the
tank surfaces, the substrate and plants in much the same manner as
Guppies and Mollies. Feed them flake foods rich in green matter such
as Spirulina Flakes or finely chopped blanched lettuce leaves.
Frequent, partial water changes should be on a fortnightly basis,
changing 20-25% of the water with fresh water adjusted to remove
chloramines and chlorine.
A PEST SPECIES
In many places around the world, Leopardfish have been introduced
into freshwater streams, ponds and
swamps in the mistaken belief that they are a suitable species for
the control of mosquitoes. In Western Australia they
inhabit the swamps and drains of Perth metropolitan area. Phalloceros caudimaculatus is also
reported from New South Wales where it is a pest species. In its
Western Australian occurrences it is reported to compete with
introduced Gambusia holbrooki and has replaced that species
as a feral pest in some locations. Be very careful NOT to remove
small fry at each water change and risk introducing them to our
If you acquire some
Leopardfish please do not put them into dams and
waterways but keep them securely inside your tank.
Put a Leopard in your tank
and keep it there!
"What You Can Do
To avoid the introduction of pests and diseases to our
environment, aquarium fish, plants and animals should not be used
for aquaculture purposes. They should be held in indoor aquarium
tanks and never be released into any waterway or the ocean.
- Do not allow any of your aquarium species, including fish,
snails, amphibians, crustaceans and aquarium weed (algae), to be
released, or to escape into any (local) aquatic environment.
- Do not use the known invasive aquarium weed Caulerpa
taxifolia as an aquarium weed species.
- Unwanted live aquarium species may be returned to the aquarium
dealer from where they were originally purchased.
- Alternatively to dispose of aquarium fish, put fish and
aquarium water into a plastic bag and into the fridge. When the
fish stops moving, put the bag into the freezer overnight
(endorsed by RSPCA WA Inc).
- Other unwanted aquarium species and weed may be disposed of by
placing them in the freezer for 24 hours.
- Due to the associated risks, the Department of Fisheries does
not support the stocking of ponds or dams with ornamental species
and would suggest that native species are considered as a
preferred alternative in these situations."
Western Australian Department of Fisheries
Aquarium plants can be
weeds, too, and introduced species ruin our native environment.
Read about aquatic, weed
Educational Application in Keeping Leopardfish
Leopardfish make an ideal
projects for schools. Keep them in at least a tank 60 cms long, 30
cms wide and 35 cms high (deep) that will hold 55 litres of water
and weigh about 65 - 70 kgs when set up with rocks, gravel and
water. Set up with a fine, gravel substrate, an internal
filter (read fishkeeping notes) and
densely planted with some leaf-cover at the surface. A tank of this size can house several pairs plus a few extra females (it is best to have
more females than males to avoid one female being chased by mating
- learning to set up an aquarium and to care for a living
creature. This project takes several months and involves
establishing the tank and maintaining it and observing the fish.
Focus on establishing a correct habitat (use that word) and
feeding routine. Older students could keep records of water
conditions, monitoring temperature, measuring pH and total
ammonia/ammonium and nitrite levels using test strips and NOT
- the monitoring of ammonia/ammonium and nitrite levels could
serve as an introduction to the nitrogen cycle.
- teaching fish anatomy by observation (no dissections).
- observing a species in terms of habitat (where it lives),
niche (what it does there) and reproduction.
- introducing the notion of "food chain"- plants are producer
organisms and fish are consumer organisms. The concepts
of niche and food-chain are connected and can be used to teach the
notion of ecological interconnections in the "chain of life".
- teaching sex education- the biology of Leopardfish introduces
"live-bearing" species that are not placental mammals.
- introducing the topic of feral species and introduced
pests (animals in the wrong habitat and niche). Consider the
risks in using introduced species in ponds and dams.
- sample local waterways for pest species.
- pest eradication projects; contact Fisheries Departments and
participate in pest control activities.
- population studies- growth rates; distribution.
- consider escape mechanisms, such as deliberate release,
flooding and over flow from ponds, dams and streams, and how to
- selective breeding- try to breed selecting for "all black"
males or an increase in yellow colouring on the body. More than one tank will be needed.