Species Article: Lake Tanganyika

Julidochromis marlieri

by Larry Rogers

My first pair of Marlier's julies came to me by way of a less than reputable dealer from Cary, North Carolina. They were sold as a matched pair and after three months the only output was that the second was nearly as large as the first. In 1977 our resources were limited and I could not figure this cute little fish out. I then acquired a second matched pair from the same spurious source. One week later the larger fish that I had assumed to be the male, and the larger of the new fish ran the others into corners and I removed the displaced pair. The largest fish proved to be female and the larger of the new pair a mature male and they spawned as soon as I cleared their adversaries. To add insult to injured pride, the smaller of the first pair and the smaller of the second pair also mated thirty days later. My first pair were two females and the second two males. Now we will endeavor to avoid your making the mistakes that I made.

Species: Julidochromis marlieri

Sexual Dimorphism: Males to 12 cm (4.72 inches), shorter, more pointed genital papillae pointed rearwards. Females to 13 cm (5.12 inches), genital papillae flat on end and longer than male'sfor attaching eggs to surface.

Habitat: Lake Tanganyika, Africa. Rocky shores with steep to medium drop-offs in the five to thirty meter depth range (15 to 95 feet). Caves and crevices in stone used for breeding.

Water Conditions: pH, 8.6; hardness, 250 to 300 mg per liter; calcium carbonate: rigid nitrogen control due to high light conditions of natural environs (stumble on nitrogen have an algae farm); temperature 26 degrees Celsius (79 F)

Temperament: While this species can be kept in an African community, a slightly crowded species tank or paired brooding tank will offer fewer problems.

The rift lake shore habitat of these fish plays a key role in setting up a successful tank. Loose rock with plenty of caves and crannies is their place of being. Fish kept without adequate shelter and surface contact never develop their greatest color nor potential. In addition, consideration must be made for their breeding habits. These fish are not the best of parents and this makes a liability of substrate materials. Any gravel that is too large becomes a deathtrap for their fry as well as a haven for debris and wastes that contribute to problems with nitrogen and pH management.


Tank raised specimens will often exhibit problems that wild specimens do not. Some disease and parasite problems that are seen in store tanks are not endemic to the natural environs of these fish. Chief among these is an ascirid worm infestation that comes to us from South American waters. These parasites will be apparent hanging from the fishes vent. I would recommend that you avoid these fish, as well as that shop, and look for more suitable stock. If you plan to breed the best approach is to buy six to ten juvenile fish from as many different sources as possible (editor's note: all fish should be from the same locale in the lake).

Quarantine all fish in separate tanks until you are sure they are not diseased. Then start mixing the water in all the tanks to insure the same water conditions and rear fish to adults.

At adult size the females will be slightly larger and more robust, that is slightly larger in relation to length, than males. Males will be more slender and more aggressive and start claiming territories and defending them. Select males from one tank and females from another and place them together in a third tank. If you use standard twenties one pair will displace the others in a short time. If they do remove the displaced pair to other quarters, if; after a week nothing has happened you should try other pairings until you succeed in a mating pair.

At adulthood two males in such confines will display and fight constantly. A dominant male will chase off any females he does not like and two females will not likely fight until the male chooses one as a mate; at that time she will run off rivals and other males.

Hierarchy in this species is a complicated affair. In unmated fish the dominant female ranks lower than the lowliest male, but; as they pair their status is elevated to the rank just below their male. For a short period after the spawn hatch there is a reversal of male female dominance and then it reverses again as soon as she stops tending fry. It makes for one hell of a soap opera in a large species tank. In a brood tank the male should be removed as soon as spawn is complete and the female as soon as spawn are free-swimming.

Both parents can be removed after spawning if certain steps are taken to aid fry development. An air stone should be placed at the entrance to the nest cave and a steady stream of bubbles kept drawing across entrance. This helps keep oxygen circulating and helps prevent fungul infestation of spawn.

If you are selecting adult specimens for tank or spawning from pet stock care should be taken to select specimens in good health. Check color, size in relation to supposed age, physical deformities, and behavior just as you would fish you had reared for the best of the lot. Poor color, clamped fins, and listlessness are good indications of stressed fish. Clamped fins usually mean disease or poor diet, together with poor color and listlessness it almost certainly means the fish will not survive long. Listlessness and poor color by themselves may just indicate stress from environs or water quality. Either way you want to test water at the shop before you take them home to avoid losses. Healthy looking perky fish are a whole lot more forgiving than fish that are already stressed.


A Tanganyikan tank should have plenty of stone. This is the first rule of most rift lake species. The substrate needs to be of fine gravel and sand to accommodate fry and prevent build up of wastes I use a shallow substrate for julies, no more than one half inch deep. Next comes tiered layers of flat stones to create a viable living space for fish. In a brood tank I build a cave in one corner and place a couple of stones against back so the fish can hide. I surround the cave with dense synthetic plants that will be removed as soon as parents are removed. In a display tank I use layers of stone up to about two inches from surface. Stones should be flat on one side and rough on the other to make them easy to stack and make plenty of caves and crevices for the fish.

There is function in this madness if correctly done. First; the bio-load (number of fish you can keep) is a function of surface area ratio so if you do not violate the surface you do not eliminate fish. Second; the heater and pumping can be hidden in rock channels and still have plenty of circulation. Third; if tapered properly to the top it looks good and you get plenty of light for viewing fish. Fourth; and most important, it is comfortable to the fish and keeps them secure and unstressed. Fifth; and of import to the keeper, this layout is as easy as any other to keep clean.

Heating is a large argument in the hobby. People try to claim that you have less water you need less heater. This is only partially true. The required heater is a function of the mean temperature of the space where tank is kept and the size of the tank; period. The stone also has to be the temperature of the water and if you let it get cold it takes a lot to warm it back up. The same thing works for you if the power goes off, all that rock does not cool quickly; but: if it is cold your water will be cold. An error on the side of caution will serve you far better than an error on the side of frugality. Trying to save a dollar on a heater could cost you a tankful of fish. Filtration is a larger issue though.

Until recently I used under gravel filtration in all but fry and brood tanks. I can state without reserve that they work well if properly maintained. I would not instruct anyone that I did not know could and would handle them in their use and care. Suffice it to say that most cannot or will not take the time to maintain a proper biology with them and they become a hazard to their fish. In fry and spawn tanks a simple sponge attached directly to a powerhead is as good as it gets. It is a high maintenance system which forces you to keep up with your fish; better attendance equals better survival.

In display tanks I have gravitated to canisters. These filters are inexpensive with good flow, available parts and media. The bio-wheel attachment has also proven valuable in helping maintain nitrogen displacement. I use one up to thirty gallons and two above that. the selection of media and set up options make them an asset.

For rearing tanks I have gone to a power filter with a built in protein skimmer. It takes fry a while to get their digestive tracts going and they leave a lot of undigested proteins in the water. The skimmer tells you at a glance whether or not a water change and diet change are in order. Accessible media and wide options make it easy to maintain and alternate filter properties for the betterment of fish health. A sponge on the lift tube is valuable in saving fry and media and increases the attention the tank requires so that you are more likely to see problems.


Fry are primarily microbe eaters the first month. Maintaining "healthy" water will provide enough food for normal brood. If this method frightens you powdered dry food will work. As soon as they are old enough they will relish brine shrimp nauplii, but they will be at least two weeks free-swimming before they should be tried. Prior to that nauplii are large enough to strangle fry trying to swallow them. As they grow brine shrimp of larger size can be served and will be readily taken.

The wild diet of these fish can be discerned by comparing their dentition to other fish we know more about. Close examination of the mouth of a specimen shows a row of flat grinding teeth. Imbedded in the lower jaw and above them in the upper jaw are similar "teeth" behind the primary row and angled more toward the throat. This same dentition can be seen in an Atlantic ocean species called the sheepshead. The sheepshead plucks barnacles and oysters and chews them up. He also eats small whelks and sea snails or clams with these ominous grinders. In much the same way the Julie plucks tiny crustaceans and snails and deals them their demise. Interestingly enough the Julie can be observed in an eating habit just like the sheepshead. When he preys upon some tough shelled critter, he chews it up and sucks down the soft parts then spits out the shell fragments just like the sheepshead. With this in mind a mixed diet should be of crustaceans, and snails. The Julie plucks his fare from lage beds and plants and takes in a lot of plant material in the process. In addition he eats some freshwater sponges, diatoms, and certain types of algal growth. Therefore we must add some vegetable components to their diets.

For most hobbyists this can best be accomplished with a high quality prepared food supplemented by frozen or freeze-dried treats. Live foods can be risky and bring many unnecessary hazards into the tank. Coupled with the fact that most hobbyists do not have the supplies, equipment, or skills to prepare their own foods; the commercially prepared food is the only logical choice.

For the insistent I recommend a paramecium culture from a good biological supply house as a starter for live feeding. The paramecia will not die in the tank polluting the water and will eat harmful bacteria and mold spores neutralizing their threat.

Until they are about ninety days old the young will not digest proteins properly. This will lead to contamination and algae blooms if not looked after. A tool from the saltwater hobby can be of a lot of assistance. Use of a protein skimmer can give you a quick reference to need for water quality improvements and help forestall problems until the change is made. Use a fast stream of small bubbles and watch the skimmer daily. A little froth in top of the tube is no concern and the aeration helps break down the proteins. When you start collecting a discharge it is time to change water. The skimmer will help keep levels down until this can be done, but do not depend on this as the only solution. If you have many fry and they are properly fed they will outrun the skimmer. Protein decay makes sugars and ammonia in the water and the algae love them. A good "bloom" will adsorb oxygen in the dark and your fish may drown.

Article copyright ©2001 by Larry Rogers, all rights reserved.


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