COMMON BULLY (Gobiomorphus
cotidianus)
The
common bully is a stout, small to medium sized fish which is
found throughout a range of habitats including lake and wetland
margins, streams and rivers.
| It
is often seen in shallow freshwater environments, where
it is often misidentified as a ‘cockabully’
(a name which is more correctly associated with the marine
triplefin). |
 |
It
feeds on a range of freshwater animals such as insects, crustaceans,
snails and small fish. The common bully matures at one year
old and probably lives to four of five years. After spawning
the larvae are swept out to sea and then return as 15-20mm juveniles.
This marine stage has been abandoned in landlocked populations.
Did
you know?
Common bullies can occasionally grow to 150mm long which makes
differentiation with the giant bully (Gobiomorphus gobioides)
difficult. This problem can be solved by counting the dorsal
fin spines- the common bully has seven or eight and the giant
bully always has six.
BLUEGILL
BULLY (Gobiomorphus hubbsi)
The
bluegill bully is a small torpedo-shaped fish with a blunt snout
and numerous spots around its head. Its colouration can vary
from brown-black to sandy brown and they often grow to a size
of 50-60mm, with the stockier male attaining a greater size.
| They
are commonly found in broken rapids within the larger braided
rivers such as the Waimakariri and often share this habitat
with the torrentfish. |
 |
They feed on small invertebrates which they pick from the underside
of rocks with their upturned mouth. After spawning has taken
place, the larvae are swept out to sea and then return as juveniles
approximately 20mm long. The bluegill bully probably matures
at one year old and lives to an age of one or two years old.
Did
you know?
The blue ‘gill’ is actually the trailing edge of
the gill cover (operculum)
GIANT
BULLY (Gobiomorphus gobioides)
The
giant bully is a heavy-set fish, which has been known to reach
a size of 240mm. It is widespread throughout New Zealand but
is only found at low elevations (they have not been found above
an altitude of 30m above sea level), which may reflect an estuarine
aspect to their spawning. It is almost always found beneath
cover such as overhanging banks, logs and large boulders, but
does emerge from cover to feed at night.
| The
giant bully has distinctive rows of small golden blotches
along its sides. It is thought that it probably feeds on
a range of small to medium sized freshwater invertebrates
and fish. |
 |
The
giant bully spawns in spring, when the male (who takes on a
jet black colouration) establishes a territory in which more
than one female can deposit her eggs for fertilisation. It is
thought that the larvae are probably carried out to sea like
many of the other bully species, and then return to freshwater
after several months as young juveniles.
Did
you know?
While the male and female giant bully may appear similar in
colouration and patterning, the female may be distinguished
by an indentation between its eyes, which if viewed from side-on
makes the eyes appear to protrude higher than the forehead.
REDFIN
BULLY (Gobiomorphus huttoni)
The
redfin bully is a small stout fish, which is widespread throughout
New Zealand. It can be identified by the diagonal cheek stripes
that are visible from a young age.
| Redfin
bullies feed on a range of stream insects, small crustaceans
and snails, and can be found in reasonably swiftly flowing
streams, |
 |
preferring
a cobble substrate in which they can find cover easily. After
spawning the larvae are swept out to sea to return several months
later as 15-20mm juveniles. The redfin bully matures at one
year of age and lives to at least three or four years.
Did
you know?
There is substantial sexual dimorphism (difference in appearance
between the sexes) in redfin bullies- the males have the bright
red colouration that the species is named for whereas the female
does not, and like several of the other bully species, the male
grows larger than the female.
UPLAND
BULLY (Gobiomorphus breviceps)
The
upland bully is a stocky and fairly distinctive bully, which
can only really be confused with Cran’s bully, a North
Island species. The male has orange spots on its cheeks, gill
covers and on the top of its head.
| The
first dorsal fin has a grey base with orange blotches on
the fin and a bright orange fin margin. There is a broad
creamy-yellow base with orange spots to the pectoral fins.
|
 |
The
female has similar patterning but without the orange colouration.
The upland bully is widespread around most of the South Island
and southern North Island and is found in a wide variety of
habitats, ranging from wetlands to lake margins to large braided
rivers. It often attains a length of 80mm and the male grows
larger than the female. The upland bully feeds largely on stream
insects but may feed on small crustaceans and snails also. The
life cycle does not include a marine stage for the larvae/ young
juveniles as is the case with many other bully species- the
larvae can be seen swimming in shallow waters. The upland bully
matures at one year of age and may live to three or four years.
Did
you know?
Large male upland bullies often have a very large head, leading
to their nickname of ‘Muldoons’ (a past New Zealand
Prime Minister!).
