Bullies

Bullies

Author: James Cooper

First published in Aquarium World August 2013

Introduction

Attractive, tough and full of character, Bullies are a hardy and easy to obtain New Zealand native fish. The name bully is short for Cock-a-bully, a name given to these fish by the early European settlers; it is thought the name is a mispronunciation of ‘Kokapuru’ the Maori word for small fish.

Cran's bully male (Photo credit Charles Fryett) 

Bullies live in a wide range of habitats throughout New Zealand and most varieties are common, although this status is being threatened by the spread of predatory Brown Trout and invasive pest species such as Gambusia as well as the reduction of habitats.  Most species are endemic to their specific habitat but occasionally species can be found co-habitating in prime areas. Bullies can change colour depending on season, mood, and breeding behaviour. Colouration can even vary within the same species for specimens found in different environments around the country so it can be a real challenge to definitively identify them.  Bullies are generally hardy and easy to obtain, living for around 3- 5 years, and they have an inquisitive personality so are the perfect candidate for someone interested in having a go at keeping New Zealand natives.

Setting up an Aquarium for Bullies

Bullies are cold water fish and need to be kept below 20°C to be comfortable.  The best way to achieve this is to keep an eye on the room temperature and if it is nearing 25°C, a few ice cubes, floating a frozen bottle of water, or a fan directed at the water’s surface can bring the temperature down.  If you are serious about keeping New Zealand natives it is wise to consider a chiller unit and although rather expensive, they allow you to keep the tank consistently cooler which will ensure you have happy, healthy and therefore beautiful fish.

Most bullies are medium sized fish (10-25 cm) so they are one of the best native species for smaller tanks.  A good minimum size tank for 3-4 adult 10 cm bullies is a standard 2ft tank (600mm x 300mm x 300mm) however they are bottom dwellers so it is more important to have a large footprint rather than a lot of height in the water column. As is standard for all fishkeeping, the bigger the better and a larger tank will allow you to keep water parameters more stable as well as allowing the introduction of other New Zealand native mid-water fish such as Inanga (Galaxias Maculate) or Smelt (Retropinna retropinna or Stokellia anisodon).

The tank substrate should be fine sand or gravel substrate and include lots of rocks, driftwood and other areas of cover for the fish to reduce stress.  Tank lighting is not essential for Bullies as they are normally nocturnal in the wild and bright lighting will usually make them run for cover. To allow for good viewing of the aquarium, dim lighting can be used and as they get used to this, they will come out more often.

Collecting Bullies in the Wild

Taking fish from the wild is a big responsibility. Once a fish is removed from a native habitat, it is illegal to release it back into the waterway (this also includes plants and invertebrates) so you must be prepared to care for it before you go out collecting.  Most native fishes are nocturnal so catching them involves venturing out in the evening for spotlighting in waterways. To capture Bullies, it is best to use a two-net approach, with one large net slowly drawn up behind the fish and another used to scare the fish downstream into the waiting net.  A good quality headlamp is a must in this situation. Another approach is to set bait traps with a bit of bread into a quiet pool or along the river bank or lake; these traps can be purchased at most fishing tackle stores. 

Night time spotlighting (Photo credit Charles Fryett)

Once captured, it is important to identify the species.  Juveniles (around the 3-5cm mark) are the best as they will adjust to the home aquarium a lot better than an older specimen. 

Once you have your fish home it is important to acclimate the fish very slowly.  The easiest way to do this is to use the ‘drip’ method favoured by marine fish keepers.  This is accomplished by placing the fish in a bucket below the tank, and using a length of standard air-hose.  Start a siphon down to the bucket, clip or a loose knot in the hose will allow you to control the flow of water - the aim is for the water to flow at around one drip per second. Once the bucket is full you can net out the fish and add it to the tank.  It is best to avoid adding the water from the bucket as it may contain high levels of fish waste.

Behaviour

Most bullies are rather peaceful and tend to be friendly to other tank mates except around breeding time, even then most squabbles are harmless.  They will however eat anything that they can swallow whole so this must be taken into account when choosing tank mates.  Apart from this, they are very well behaved and inquisitive, known for spending a lot of their time watching the outside world and enjoying vantage points on which to perch for a better view, often pushing each other out of the way to get the best spots.

Feeding

Most bullies will transfer onto a diet of standard dry food quickly, however it is best to use a sinking pellet type rather than a flake as it holds together better and causes less pollution in the tank.  Frozen bloodworms are useful as a treat but should not be used as a staple diet as they are nutritionally lacking.  Another good alternative is a prepared food with ox heart and a variety of vegetables, there are a range of recipes out there and a quick search will provide you with one you can use.  The benefit of this food is that you can control what goes in to it and ensure your fish get a balanced diet. If available, live food is a great option, there is a variety of easily cultured foods available such as daphnia, whiteworms, blackworms, maggots or earthworms which provide a lot of nutritional value as well as promoting the fish’s natural hunting behaviour.

Cran's bully eggs 20+ days (Photo credit Charles Fryett)

Breeding

All bullies are cave spawners.  Normally during spring or summer the male will set up a territory within a cave-like structure, normally the side under a rock or log. The male adopts a dark colouration, almost black in some species.  The female will deposit a number of eggs inside the cave and then leaves so the male can guard the nest until the larvae hatch.  This takes up to several weeks, the time is temperature dependant.  Some species spend their larval stage around the place they were born; some migrate down to sea and return once they have reached a certain size.  One (the Tarndale Bully) even has free swimming pelagic larvae.  The only types that can be successfully bred in the home aquarium are the Upland bully and the Crans bully.

Common Bully - possibly male (Photo credit Charles Fryett)

Common Bully

Gobiomorphus cotidianus

Found throughout NZ and the most common bully as its name suggests, it is found in lowland areas around coastal rivers and lakes.  It is normally not found far inland as it is not known to be a great climber like some of its couterparts.  This bully is one of the best for beginners due to its amazing hardiness - this is not to say it should be mistreated as a well kept specimen is a sight to behold.  Grows up to 15cm, matures at around one year old and lives for 4-5 years.  It is a sea run spawner but there are landlocked populations that complete their entire lifecycle in fresh water.

Giant Bully (Photo credit Charles Fryett)

Giant Bully

Gobiomorphus gobioides

The largest of the native Bullies gets to a length of 24 cm and is commonly found in the lower reaches of rivers and even into brackish water of estuaries. They rarely travel far upstream from their home habitat.  Juvenile Giant Bullies and Common Bullies are hard to distinguish from each other; the rule of thumb is that Common Bullies have seven spines in their first dorsal fins and Giants have only six.  Another clue is that the lower jaw of Giant Bullies extends past the top lip where as in Commons the jaws tend to be more equal.

Giant Bullies can be a bit aggressive to other smaller tank-mates and they also like to hide under overhanging banks and in heavy cover so they not only require a larger aquarium than other bullies, but they also appreciate adequate cover and hiding places.

Red fin bully (Photo credit Liam Winterton)

Redfin Bully

Gobiomorphus huttoni

The jewel of New Zealand native fish is the spectacularly coloured Redfin Bully where males of the species have brightly coloured finnage and variable body colouring with bright yellows, reds and iridescent greens. During breeding they will turn a solid black with a bright green edge to their first dorsal fin. Females have fewer colours but still have the diagonal facial stripes that are a tell-tale sign of this species. They are a smaller bully only reaching a maximum of 122mm (females are smaller growing) so are perfect for the smaller aquarium or species only tank. They are found NZ wide and are well accomplished climbers found well inland even past significant barriers such as waterfalls. Unfortunately, they are a sea-run² fish so have not been successfully bred in the home aquarium.

Bluegill bully (Photo credit Stella McQueen)

Bluegill Bully

Gobiomorphus hubbsi

This little stunner is an inhabitant of faster flowing water and loves a strong current to play around in. Bluegill Bullies have a longer more streamlined body-shape that is perfectly adapted for living in fast flowing rapids of new Zealand rivers. The Bluegill Bully is also a smaller growing species, only reaching 93 mm. An aquarium for these beauties requires a strong water flow and a lot of surface movement to ensure high amounts of oxygen like those found in its natural habitat. With careful placement of stones you can create calmer areas for the fish to rest and feed right. Found New Zealand wide, the Bluegill has a sea-run larval stage and are very short lived, living only to around 2 or 3 years maximum.

Cran's Bully male in breeding colours (Photo credit Charles Fryett)

Cran's Bully male with large female (Photo credit Charles Fryett)

Cran's Bully

Gobiomorphus basalis

Short and squat, these fish can only be described as cute. Crans Bully bodies are mottled with sandy browns and olive greens, the males sport a bright pink/orange margin to their first dorsal fin. As the males age their heads become more blunt and bulbous. They are found mainly in inland rocky streams throughout the North Island except in the Bay of Plenty region from Waihi to East Cape. These Bullies are one of the landlocked bullies that can be successfully bred in the home aquarium. It is one of the most common species in the North Island and  grows to a maximum of 92 mm.

Upland Bully (Photo credit: Stella McQueen)

Upland Bully

Gobiomorphus breviceps.

A distinctive bully with a lighter grey/brown base colour than most of the more coastal bullies and irregular brown patches and orange/brown spots. Males are stouter and have a blunter head that gets more blunt with age and a orange fringe to the first dorsal fin and a light orange patch at the base of the pectoral fin. Females lack the orange. As its name suggests it is found in upland areas throughout the South Island and in a few rivers and streams of the southern North Island. It is a fully freshwater species and can be bred in the aquarium.  This is a slightly larger species growing to a maximum of 135 mm.

Tarndale Bully

Gobiomorphus alpinus

Here more out of interest than for actual keeping, the Tarndale Bully is NZ's smallest bully with a maximum recorded size of 75 mm.  It is also interesting in that its larval stage, although freshwater it is also pelagic¹.  It is only found only in the Lakes of Tarndale Station in Molesworth, near Marlborough and in the upper Clarence river system and Wairau river. The Tarndale Bullis are slender and rather big-headed but otherwise hard to distinguish from the Common Bully. They are not technically protected, as are none of our living native freshwater species, but considering their rarity, it would be considered ethically wrong to attempt to collect it without proper consent and knowledge of the relevant authorities. Being only found on private property, trespassing laws would also apply.

¹ Pelagic fish live near the surface or in the water column of coastal, ocean and lake waters, but not on the bottom of the sea or the lake. http://en.wikipedia.org/wiki/Pelagic_fish

² Sea run – Spawning takes place in fresh water and after hatching the larvae are swept out to sea.  As juveniles they return to fresh water where they spend their adult lives.

Further reading on Bullies:

The Reed Field Guide to New Zealand Fishes; R. M. McDowall; 2000

Ikawai – Freshwater fishes in Maori culture and economy; R. M. McDowall; 2011

The New Zealand Native Freshwater Aquarium; S. McQueen; 2010

A Photographic Guide to Freshwater Fishes of New Zealand; S. McQueen; 2013 

FNZAS Native Freshwater Fishes; FNZAS/C. Fryett; To be published

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