While the Mbunas and Haploids of Lake Malawi would be more familiar to most aquarists of the ACT and surrounds, many fish from Lake Tanganyika are commonly found in local fish shops. The Lemon Cichlid (Neolamprologus leleupi), the Princess Cichlid (Neolamprologus brichardi), and several species belonging to the Juliochromis genus and Tropheus genus are commonly kept. Perhaps the most famous resident of this lake is the Cyphotilapia frontosa. This gentle giant is a lump-headed fish with six or seven vertical dark stripes on a white background, and is a must have for many African Cichlid aficionados. Over the years, many of these fish have graced my tanks. However, there was another branch of the Cichlid family that I had long wanted to keep. A group of diminutive but plucky fish that are not known so much for their large size and flashy colours but for their great character and interesting habits the Shell Dwellers of Lake Tanganyika.
As many of you would know, Lake Tanganyika is the home to some of the most spectacular and interesting aquarium fish available. This is Cichlid territory. Tanganyika is the sixth largest lake on Earth. It is 676 kilometres long and 64 kilometres across at its widest point. At 1,463 meters deep, Tanganyika is the second deepest lake in the world, behind only Lake Baykul in Russia. The water conditions encountered in the lake are somewhat unusual. While the temperature of a constant 26-27°C is reasonably typical of tropical climes, the water is very hard and alkaline. The pH ranges from 8.7 to 9.4 and the carbonate hardness is 200 to 240 parts per million. Fortunately, replicating this environment is a very easy task for the modern aquarist – but more on this later.
I first became acquainted with the Shell Dwellers by reading the Sydney Cichlid Society. The owners of these fish wrote about them with such unmistakable passion and affection that I felt drawn towards keeping some. There are several species of Shell Dweller but one of the most readily available is Neolamprologus ocellatus (normally referred to as ocellatus or just occi).
Ocellatus grow to five centimetres, although females rarely exceed 4 centimetres. Colouration is basically fawn with a blue-purple blaze through the body, which is more or less apparent depending on the mood of the fish and the quality of lighting. Ocellatus are quite stocky and have a largish head. Further, there are two main subspecies. The gold form has a general golden hue whereas the blue form has distinct blue colouration around the head. The male of both subspecies has a dorsal fin with a slight gold rim. Females have a slightly more prominent white rim on the dorsal. Although, you may hear of the existence of the black ocellatus, this is actually another species, namely Neolamprologus meleagris.
I was determined to buy a pair of ocellatus on the 2002 CDAS trip to Sydney. Finally, I tracked some down at a reasonable price in Liverpool Aquarium. Upon arriving back at Eejays place in Canberra, I inspected my fish and while my other fish appeared very healthy, the ocellatus had that distinctive if you want me to live then youd better get me in a tank real soon look. The fact I did not get a speeding ticket on the way home, I put down to good luck. While I did not have a specific tank set up, my 3 ft. community tank was slightly alkaline and hard enough that I thought that it would suffice as a temporary home.
For a month or so my Occis thrived. These little guys are real characters. I placed a few shells that I had gathered from beaches over the years into the tanks. The Occis would find the shell they wanted and basically bury it so that just the tip was sticking out of the gravel, with just enough room to afford ingress and egress for a small Tanganyikan Cichlid. They will take a variety of foods, including flake, but just love Daphnia.
While I have never actually seen them harm another fish, they defend their territory with much vigour. Any fish, fingers, cleaning magnets or whatever that stray within a few inches of their shell get the same treatment, a firm nip. Believe it or not, this grumpy behaviour is very endearing. The male and the female were quite interested in each other and would even tolerate the odd visit to each others shells. It seemed just a matter of time before I would have a brood of young ocellatus. However, fish keepers being what they are and Canberra winters being what they are, disaster struck. Yes, I left the heater off after doing a water change. Ok, I admit that this is a crime against fishkind but I bet that most of you have done the same at some time or another. Anyway, while the Tetras, Corydoras, Glass Catfish and Rainbowfish were not happy about it, the 18° water temperature was quite fatal for my male ocellatus. Big lesson, these guys do not like cold water.
For another nine months, I kept a very lonely female. It got to the point where I really felt sorry for her and so I set up a 2 ft. species tank. The substratum is white sand and I placed several shells and some rocks for cover. The only special water treatment required was the addition of a teaspoon or two of water conditioner for every 10 litres of water. This is basically a mixture of various salts and carbonates that buffer the water. This increases the water hardness and stabilises the pH at around 8.5.
Now, while my occi liked her new accommodation, there was something she was missing. Despite the $35 price tag, I ordered some Neolamprologus ocellatus (gold form) from Jem Aquatics. The first lot that Bob ordered died in his quarantine room – this confirms for me that they do not travel well. He kindly ordered some more in for me and so I bought two Romeos for poor Juliet. Again, despite being a relatively short trip, they did not look at all healthy when I got home.
The romance was a torrid but quick affair. After about five minutes of jaw locking, tumbling around in the sand and generally antagonist behaviour, the territories were established. One of the males hid behind the filter and basically stayed there until I rescued him a month or so later. The other male claimed a shell and the female managed to hold on to her original shell. While I did not observe the spawning, two weeks later, I had just done a water change when I noticed a few tiny fish wriggling out of the shell. You little ripper!!! When mother gave the signal, the little fry of about three to four millimetres would swim out and sit on their bellies on the sand waiting for food but at the soonest sign of danger she would herd them back into the safety of the shell. No doubt a great defence against predators.
As is typical for me when faced with a situation where I need further information, I consulted the great electronic oracle, the Internet. The advice from the Sydney Cichlid Society discussion forum varied. Some said leave them in there and take them out when the parents spawn again (to avoid sibling predation) and others said take them out straight away. The latter view seemed to attract the majority of support and so I set up an 18 inch tank with a small air powered corner filter. Naturally, the water was sourced from the original tank. Apparently, the parent fish have a habit of diving in the shell after the fry when really threatened. The key is to distract the parents with a twitching finger. The parents shoo the fry into the shell and proceed to try to remove the offending finger (from their territory). While this is going on and using the other hand, grab the shell and place your finger over the opening, lift up and place in the other tank. As I found out, while this sounds difficult, it is in fact quite easy.
My first spawning turned out to be a large one, with 20 young fish (subsequently, 10 to a dozen seems to be the average). The fry are quite independent from a young age and will take small Daphnia, newly hatched brine shrimp and crushed flake. The easiest way to sort the big Daphnia from the small is to place a very fine fish net on top an ice cream container with a less fine fish net on top of that. Simply pour the Daphnia through and you will catch the big ones in the top net while the small ones will be caught in the smaller net below. The fry grow relatively fast when this food is supplied.
After three months, the fry have been moved into my four foot growing-out tank and are more than two centimetres long – they are starting to develop their very own grumpy personalities. Several have even taken up residence in their own shells. They are growing fast and there is another brood in the 18 inch tank. I have decided to leave the most recent brood with the parents in order to observe their behaviour when the fry get older.
Anyway, as you may have gathered, I cannot recommend these fish highly enough. They are comical, tenacious and compatible with most community fish (I even kept them with Cardinal Tetras). They are fairly tolerant to a variety of conditions but I would not put them in soft acidic water. While they are not a flamboyant or overly colourful fish, their shell dwelling lifestyle makes them a fascinating pet. In a nutshell, occis simply rate 10 out of 10 on the personality scale.