Kribensis: The river rainbows

Cichlids often come with a cost. Some beauties become giants, while others carry psychotic degrees of rage. Some like their water softer than marshmallow and others harder than granite. They are a fickle crowd.

One small group of African cichlids sits somewhere close to a perfect balance. As well as being quite small, their aggression only flares when their offspring are confronted by offending mouths.

They have sublime colours; so much so that their common names reflect this.

They don’t pick on their females, feed willingly, and, if provided with a little privacy, will quite happily go and spawn. And once they have, they’re happy to raise the fry up themselves. These are the Kribensis — fish that have become an aquarium standard for the community keeper.

Technically, the original Kribensis was a single species ­—Pelvicachromis taeniatus — which was originally misdescribed as Pelmatochromis kribensis (which also managed to gobble up what is now Pelvicachromis pulcher in the confusion) and later revised.

But, just to really confuse things, many aquarists choose to use 'Kribensis' as a colloquial catchall to refer to any of the seven species of Pelvicachromis. For the majority, P. pulcher is the 'standard' Krib and I use that association here.

P. pulcher is an aquarist’s dream. It carries the most startling colours — alternative names are the Palette cichlid, or the Rainbow krib — and it has the pointed trailing fins that one would expect from a far more expensive species. If I had to design the perfect domestic fish from scratch, it’d likely be a Krib.

The only possible drawback to these fish is their innate shyness. Kribs are not especially bold, though there are rare exceptions. To see them at their best, the inclusion of dither fish will be needed — more on them later.

All Pelvicachromis species prefer riverine conditions and are restricted to the African continent: chiefly West and West Central Africa. Only in the rarest of cases do they make an appearance in some slower moving or static flooded area.

P. pulcher inhabits a range from Benin, into Nigeria and Cameroon, and always in similar habitats.

Never brackish…

There’s a myth that to this day keeps doing the rounds, unsupported by sound referencing, that Kribensis are found in brackish waters. In reality they cover a vast delta that stretches from around 150km inland to the sea, but repeated surveys have shown that Pelvicachromis are only found in the fresh, usually soft waters, and never in brackish conditions.

The idea of the brackish Krib seems to have arisen many years ago, possibly started by Baensch in his aquarium atlas, but has not been subsequently corrected.

To put the record straight, every bit of quantifiable evidence points strongly at Kribs being obligatory freshwater inhabitants that are quite unsuitable for life in a brackish system.

In studies of their range, the number of collectable P. pulcher substantially drops off as researchers come progressively closer to brackish water regions.

So these fish are not big fans of salt, then.

'Frynapping' (Picture of juvenile above by Tino Strauss, Creative Commons)

Changing sizes of Kribs are found at different points of rivers. The shallowest regions are home to the smallest as well as large numbers of females. Where in most areas a one male to one female ratio is maintained, in shallow regions this tilts hugely in favour of females and 1:2 is the norm. This is most likely a response to predation issues because natural eaters of the Krib — Lates, Hepsetus and Hydrocynus, for example — avoid such shallows. For a young or female Krib, there is safety in a few inches of water.

To further decrease risks, especially those presented to their own offspring, Kribs are known to 'frynap' each other’s offspring or rather to take on board clusters of fry from other breeding pairs. It is suspected that increasing numbers in a brood dilutes the risk of losing one’s own fry to a predator attack.

The fluviatile habitats of Kribs are quite fast moving, with water rushing past at somewhere between 10-50cm/3.9" -19.7" per second. That’s hardly a gushing torrent as you’d find in whitewater areas but a lot livelier than you’ll find in the majority of aquaria.

Such a flow affects the environment that the fish live in, so in this case the presence of fine leaf litter or mulm, which is where Kribs live, is sometimes reduced. Instead, riverbanks tend to be teeming with plant life, and the only debris found is large and heavy with smaller pieces being washed away.

Rounded stones and heavy branches are what a wild P. pulcher would recognise in its habitat, along with a clutter-free substrate of fine and coarse sand, and occasional larger leaves.

Dangerous origins

There are very few wild P. pulcher in the hobby, and equally scarce are wild specimens of the other Pelvicachromis species, though they do arise. The reasons for this are simple — their origins are dangerous places where the risk of murder or kidnap, particularly the kidnap of a wealthy fish scientist or merchant, is great. Boko Haram kidnappings of western workers are frequent.

To our benefit, the fish breed quickly and prolifically enough for the hobby to be supplied exclusively by tank produced and farmed individuals.

To our loss, we run risks of inbreeding and miss out on huge amounts of potential information about their wild nature.

For example, we know of many colour variations in males of any species of Pelvicachromis, and several populations of each species appear to exist in different regions. It’s not uncommon to see Pelvicachromis species offered with names hinting to their tribe and provenance. One might see P. taeniatus 'Nyete' or 'Moliwe' which will differ substantially to P. taeniatus 'Niger red'.

There are various communities and forums dedicated to the identification and breeding of these variants, and if interested I’d encourage you to investigate because there’s more to it than I could hope to even give an overview of here.

The Krib’s crib

Setting up a tank for Kribensis is easy. Whether you want to slip them into a community or go for something more biotope-based, you only need worry about water parameters for these fish to fit right in.

Plan for a tank of no less than 90cm/36" long. If going for a single pair, 60cm/24" should be

the smallest you use. Though Kribs don’t get huge, they’ll be grateful for extra space.

If planning on biotope, then sand, branches and cobbles are the prime choice of décor. For planting, provide opulent growth. Tangles of Crinum species and banks of Cyperus, Ceratophyllum and Ceratopteris, plus ample Anubias and Bolbitis fastened to the wood will provide abundant cover.

For authentic fish, think of Brycinus longipinnis tetra, and Pareutropius buffei catfish (above). Aphyosemion gulare killifish are abundant in the same areas as P. pulcher and make a pleasing enough companion.

The water for wild Kribs needs to be neutral to slightly acidic with a pH value of between 5.6 and 7.0 and a hardness as low as 2-3°KH.  Temperature should be somewhere between 24-27°C/75-80°F for daily maintenance.

However, that’s wild Kribs and the farmed counterparts are considerably more tolerant of a much wider range of conditions.

In the community tank aim for water that is neutral pH, of hardness up to 7°KH, and has a temperature of about 25- 26°C/77-79°F.

Avoid housing community Kribs with other cichlids that may not share the laid-back approach to life. Fish like Blue acara or Jewel cichlids are likely to pick a fight with a Krib and should be avoided.

Likewise, catfish careening about the base of the tank and ousting Kribs from their homes will not be appreciated. House them alongside smaller, peaceful fishes with similar water tolerances for best effect.

One feature that is an absolute must for the Krib tank is the cave. Kribs love to have a home of their own in which they will eventually pair and spawn. This can take the form of an old terracotta flowerpot, a hollowed coconut shell, a custom designed catfish cave, or even a length of large bore hosing.

Whatever you opt for, ensure the Krib has a safe retreat to which it can return at any time. Bare, open tanks will always lead to disaster.

Making rainbows

One thing that everyone needs to have a stab at is breeding Kribensis. Few fish display such a vibrant spawning dress, and it is rare for a pair to be so aggressive that either partner is wounded.

Sexing P. pulcher is child’s play, and in the exceptional, rare circumstance that your supplier can’t do it for you then you can step in and easily do it yourself.

In adult Kribensis, the male (pictured above) is always the larger of the pair, reaching up to a maximum of 12cm/4.8". Clear indications of his sex are the design of his tail, which will be slightly diamond shaped. His dorsal and anal fins will be trailing and pointed at the tips. Some keepers like to base sex on the presence of ocelli (eye spots) in the dorsal and caudal fins, but this is not reliable.

Females can display these frequently; even more so with farmed variants.

The male will sometimes have a pronounced red throat, starting at the chin and moving right down over the belly.

Females (pictured above by Tino Strauss, Creative Commons) are always smaller, up to 8cm/3.1" or so, and squat by comparison. They lack the male’s torpedo shape. As long as they’re not stressed they’ll exhibit brighter colours than males too, though note that in the female it is only ever the belly that becomes red and not so much the throat.

The female’s fins are also indicative — her having a rounded, spade shaped tail and rounded dorsal and anal fin tips.

Breeding takes place on the inside roof of a cave after a dance and display during which the female forms a vague 'L'-shape with her body. Spawning activity can sometimes be encouraged by pushing the temperature up a couple of degrees but to no higher than 27°C/80.6°F. Without caves present, expect nothing.

When the pair spawn, there can be some defensive behaviour from the male, who protects the immediate area while the female tends to the young. For the first nine to ten days she may make no appearance at all and will hide away while the male patrols.

At this stage, removing any community bottom dwellers would be wise because they may be struck by the defensive male — especially inoffensive fish like Corydoras that may stumble into the target area quite by accident.

On emergence, you should note quite large fry — which is great as it makes feeding simple! Artemia nauplii are taken (though not ideal), and finely crushed, protein-rich flake food and fry food is soon accepted. Expect the parents to stay with the young for three to four weeks until they eventually start to drift apart.

You need do nothing but feed, sit back and watch as all of this unfolds. And being peaceful, colourful fish in high demand, many retailers are even sympathetic to rehoming your offspring. Get them up to a decent size and you may even be offered a credit note for your efforts.

Note that the pH value of the water the fish breed and rear in has an affect on the sex ratio of the young. At a pH of 7.0, there’s an approximate balance of males to females, though as the water becomes more acidic the number of females increases considerably.

Fresh and green food for thought

All Pelvicachromis species get referred to as omnivores in stores, but the reality is of a strongly herbivorous fish with a taste for algae types and one that ingests a fair amount of sand into the bargain.

In studies conducted on wild fish, crustacean food was found in the bellies of under a quarter of all Kribs with detritus and higher plant matter (fragments of leaves and stems) being found in the majority.

What might be of surprise is the amount of algae ingested. Diatomaceous algae (think the sludgy algae that sometimes occurs on substrates) featured highly, as did blue-green and plain green algae types.

In every single belly looked at, sand was present making it rather clear that the fish were ingesting substrate as they rooted around for algae and detritus. It’s suspected that they even digest the nutritious biofilm that forms on individual grains.

In the aquarium, plant-based foods should be abundant, and Kribs will eventually disassemble softer leafed plants in the tank.

When choosing a food, look carefully at the packaging. Many ‘plant’ foods or algae flakes actually contain very little greenery, and the main ingredient will be fish.

Ideally, you want a veg-heavy flake food if you want fish that aren’t distorted or stunted.

Supplement with plenty of fresh greenery such as blanched spinach and dandelion, flaked pea, and any of the seaweed products frequently marketed for marine keepers.

If you are supermarket shopping, don’t be shy; acquire a little nori seaweed for your fish — I am sure the irony of being fed a sushi ingredient will be lost on them…

What the dither?

Dither fish are smaller fish and cohabit sympatrically with other species. They act as a good indicator to other fish on the presence of predators. Like a landed flock of birds, dither fish will scatter and vanish when threatened.

This presents an excellent visual guide for those fish with the sense to watch them. When dithers are out and about, it’s a good sign that the coast is clear, but if they suddenly disappear then it might be time to do the same!

Small dither fish in aquaria are often species like Zebra danios that are always out and about and immensely active. Their presence reassures more nervous fishes and encourages them to come out of hiding in to the open.

Be careful not to choose dither fish that are too ravenous or aggressive. You may find that adding too hostile a dither fish to a tank has the reverse effect, and the very fish you want to encourage out becomes all too aware of the risk to its fins if it does emerge.

Factfile:

Common name: Rainbow Krib.

Scientific name: Pelvicachromis pulcher.

Origin: Nigeria, Cameroon, Benin.

Size: Male 12cm; female 8cm.

Notes: Widely available, though wild caught specimens rare.

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