The Government of Nigeria, assisted by the United Nations Development Programme and the Food and Agriculture Organization of the United Nations has been engaged on a project concerned with research in the Kainji man made lake.
The purpose of the Kainji Lake Research Project was to assist the Government in the comprehensive development of man made lake resources through research and purveys, the results of which will be made available to all regions of Nigeria, Research was conducted in the fisheries, agricultural and socio-economic aspects. It also studied Public Health problems and means of developing the Borgu Game Reserve into a national tourist attraction.
The long range objective of the project as far as fisheries in concerned in described as follows:
“To establish a fishery research programme that will enable the fullest utilisation of the lake's and downstream river's fish crop on a maximum sustained yield basis. This will require limnological and biological research, also trials and demonstrations of now fishing boats, different fish catching, processing and marketing methods.”
As part of the project operation, FAO assigned an Aquarium consultant Mr, Edward J. Peterson, for a short assignment to advise on planning aquarium facilities at the Kainji Lake Research Centre, mainly for endemic species. This would function both an a public aquarium to help stimulate tourism and also house a research aquarium facility.
When the Consultant arrived at his duty station, the Director of the Kainji Lake Research Project, Dr. Sagua, had not yet selected the site for housing an aquarium which was to be part of a new building complex and which would have the dual functions of public display combined with research, The public display section was intended to complement the area tourism concept, including wildlife observation trails in the Borgu Game Reserve. The size or number of the aquarium tanks was not determined and the use of lake water presented infiltration problems. (Nells were inadvisable owing to the annual heavy load of colloidal clay.) It was decided to compile a list of species, numbers and weights of display fish no that the number and size of the tanks could be estimated. In turn this would give the basic data required for calculating water volume requirements, pumps and water line sizing and filtration systems design.
In the meantime, the Consultant examined reports dealing with the Lake Kainji area, thus obtaining details of the chemical, physical and biological factors which might influence aquarium design criteria. He selected several taxonomy keys for fish of the area along with reports dealing with fisheries and fish populations at the lake (Tables 1–5). Selected representative species from these tables were used to develop data, for other tables containing calculated tank volume, filter sizes and water turnover rate (Tables 6–8), The latter indicated that about 12 000 gallons of display area, 3 000 gallons of quarantine area, 5 000 gallons for research tanks and a 5 000 gallon supply reservoir would be required.
The Consultant had a meeting with Mr, H.W. Obinya and his associate Mr. Omotoska architects from Lagos, for discussions on general aquarium design. The concept of an aquarium complex at the Centre of the new headquarters building was reaffirmed. An “Outline of Aquarium Design Criteria” was then developed, forming the basis for a questionnaire, later distributed to the staff members concerned (Appendix 1). This was the initial vehicle for their input and ideas regarding their needs. The Consultant then visited the installation at the Shaguna substation which is situated half way up the western lake shore and is operated in conjunction with the Kainji Lake Research Centre and the University of Ibadan. Discussions were held on the monitoring of electrical characteristics of Mormyrids. Lake Kainji has a considerable population of several species of Mormyridae. All have the capacity to give off electrical impulses of varying intensity and frequency. These charges are probably used somewhat like radar or sonar or locating food and avoiding enemies in the turbid waters.
The Consultant had previously monitored several species of African and South American fish possessing this ability. In these experiments, two carbon electrodes 6 inches by 12 inches in 30–100 gallon tanks were connected to the high impedence jack of a 25 watt audio amplifier. The output of the amplifier went to an 8 inch 8inch speaker. There appeared to be no reason why, with proper impedence matching, an amplifier output could not be connected to a pen recorder.
The basic closed system aquarium with its air lifts and filters was described by the Consultant and discussions took place on feeding problems of some specimens at the substation. Several fish had adapted their feed from the natural chironomid larvae to maggots. Others however refused to accept ouch a large and rather tough feed. Bottom fauna in the Kainji mud is very scarce and no tubifex were available locally. The Consultant suggested fruit fly larvae as there is an abundance of these diptera.
During the regular weekly seminar, the architect Mr. H.W. Obinya requested the return of the completed questionnaires, passed out the previous week.
Lake Kainji is very turbid from August through December. Though the drinking water is treated with alum and pressure filtered through sand by the National Electric Power Authority plant, it remains milky. It would seem that only diatomaceous earth filters could' provide clarity for an aquarium. This hypothesis should be checked experimentally with a small portable swimming pool filter which uses diatomite. If the test is successful a large stationary unit should be used on the raw water. This could be done in an under-the floor storage reservoir. A 5 000 gallon reservoir could supply an adequate margin of safety. In emergencies two of the largest tanks could be dumped and quickly refilled. A D.E. filter such as a commercial swimming pool type, capable of recirculating the reservoir water at least twice per hour, while removing particles above 3–5 microns might be used. Provisions for D.E. disposal must be included in the design. Diatomite should not be discharged into a septic system, A block diagram of a possible system is shown in Figure 1.
A description of D.E. filter - operation and drawings of typical units arc included in manual “Aquarium Management” compiled by the Consultant which he left at Kainji (7).
A turbid water supply also means that a closed tank system would be the logical choice. Cloned system aquariums have no continuous fresh water flow from an external source. Each fish tank has independent filters with no water contact between tanks. Closed systems are also advantageous because they reduce chances of spreading disease or parasites through the aquarium complex.
Display tank volumes from tables 6–3 total 10 420 gallons. An additional 35each 10 to 40 gallon aquaria plus 20 each 50 to GO gallon units should be included. This would furnish space for the numerous species of small tropical fish. For example the Genus Barbus has over 280 reported species in Africa. Many of these arc endemic to Kainji and the Niger River. Examples of these and other local small species or even juveniles of the larger varieties could be worked into, pleasing displays.
The sizes and numbers of research tanks can be adjusted to the needs of the Project at a later tine. Space for the wet lab tanks however should not be overlooked.
Quarantine holding tanks, with a total volume of 1/3 the display tanks, would be desirable. It would be foolish to introduce disease or parasites in incoming fish, into tanks containing prize specimens. ?7ew specimens should be isolated, observed and treated if necessary prior to being put on display,
Airlift pumps should be used wherever possible (Fig.2 & Table 9).They are easy to build, dependable and efficient. Some units consist of a 3/8 inch diameter air stone inserted in a 3/4 to 1 inch diameter tube. In practice, the efficiency of an airlift depends on (a). the uniformity of dispersion of air in the liquid within the lift. (b). The percentage submergence; that is that length plus the distance above the surface the fluid is to be raised. A more detailed look at airlift is contained in pages 30–32a of the “Aquarium Management” manual. Airlifts should be used to circulate water through all fish tanks and all biological filters.
Biological filters, both bottom type and external units, are the most widely accepted systems in modern aquariums. They are simple to service yet provide excellent control over metabolic wastes in a closed system. Ammonia, the most objectionable nitrogenous waste can be converted to nitrite and nitrate through bacterial action in the substrate. A good substrate consists of 75% volume of 2–5 millimetre silica sand mixed with 25% crushed oyster shell or other suitable calcercous media. Calcium acts as a buffer, maintaining an optimum pH for nitrification. Design criteria for filters are shown on Table 10,
Biological filters can be cleaned by periodic backwashing. A reverse water flow through the filter, while stirring the media, allows the dirty water to be drained into a floor trench. Internal or bottom filters can be cleaned by stirring the bottom media with the flow from a portable D.E. filter.
At least five portable diotomite filters should be available. Three each 50–75 gpm units for the large tanks and two each 10 gpm filters for the small tanks. These arc also available from swimming pool equipment companies.
A schedule of replacing at least 10% of the water in each tank once a week should be maintained. This will, in most cases, control dissolved waste product accumulation in the tanks.
All waterlines must be composed of inert materials. Schedule GO P.V.C. can be used in most cases on lines under 3 inches. The valves should also be inert, Kainji Lake water is relatively soft, consequently able to pick up heavy metals such as copper and zinc, These can be very toxic to fish.
An adequate work space of at least six feet should exist between the back of the display tanks and the quarantine tanks. This will allow easy movement of new specimens, tanks, equipment and bulky materials by hand truck. The operations floor should be about three feet above the viewing area floor. Level access to an outside loading dock should be provided.
Stairways with locked doors can allow passage for aquarists between operations and the public area.
Display tanks 200 gallons or more need ample bottom drains. Tanks to 175 gallons can be commercial glass units. Medium tanks up to 1 000 gallons could be fiberglass. These are commercially available. Large tanks over 1 000 gallons will likely require re-enforced concrete. Glass bearing surface should be true in all cases. A table of dimension is included on Table 11 and in the Aquarium Manual on pages 40–49.
Tanks with species tending to jump should have provisions for restraining the animals. A 12inch wide screen which lies horizontally along the back and side walls and over the water helps in some cases. Another method is a netting curtain attached to the ceiling and rim of the tanks.
Choice of tank arrangement or placement should be such that aquarists can work comfortably behind the scenes. They must be able to clean the glass, remove uneaten food, dead or sick specimens and be able to adjust or change decorative materials.
A floor trench about 6 incites deep and 12 inches wide Should extend around the perimeter of the back of the display tanks. It should have drains with sand traps.
Ample electric outlets arc needed at each tank position (500 gal. +). A double socket on each side of the tank and one on back wall behind the tank should suffice. Even small tanks must have electrical outlets for lights, etc, near enough to eliminate using extension cords. Electric outlets must not be near the floor; eye level is convenient. All must be grounded and if possible water resistant,
Water and air supply lines should be suspended from the ceiling above the tanks. Valves arc needed at least above tanks over 300 gallons.
Direct sunlight should be excluded from the operations and viewing areas, sunlight accelerates algae growth increasing maintenance. Lighting for tanks over 500 gallons should be mounted in a way the fixtures can be moved from the way while working on a tank.
Two sinks located conveniently on the back wall, will allow for cleaning small tanks, decorative materials and utensils,
A food preparation area must be considered. Furnishings such as a freezer, refrigerator, sink, blender, hot plate, cabinets, cutting table and cutlery are bare essentials. In many cases natural food cannot be obtained for all species. Most fish can be taught to accept a formulated substitute diet. The ability to prepare a wholesome food for your specimens improves chances of maintaining them in optimum condition. A paper entitled “A Meal-Gelatin Diet for Aquarium Fish,” by Peterson, Robinson and Willoughby was left at the Kainji Laboratory for future reference (8).
A disease and water quality laboratory should be planned in the research section.
Storage for dry materials such as sand, oyster shell, diatomite, decorative materials, small equipment and utensils should be provided. Shelving will help keep this area neat.
Aquarists should have a crew room with lockers, fountain, shower and water closet. A desk and filing cabinet in this area would offer apace for keeping records.
A small shop is necessary for minor repairs on equipment, tools, plumbing and display fabrication. It is difficult to envisage an aquarium without a reasonably well equipped chop.
The equipment room for standby generators and air blowers should be adjacent to the operations area. Sound proofing for this area should be used to the extent possible to relieve the staff of the noise of operating machinery. A 50 cfm at 15 psi blower should suffice providing there is another similar backup unit, Emergency gasoline power unit rated at 2.5KW would drive these blowers in the event of a power failure.
Tank design and placement with consideration for a smooth natural flow pattern in essential. Examples of tank configurations in aquariums are shown on pager; 27 through 29b in the Aquarium manual. Arrangements should offer variety in size, type and placement contributing to an aesthetic authentic display.
Exhibits must be pleasing and artistic to be effective. An axiom is avoid artificial “gimmicks” that in themselves have no meaning - use natural looking material throughout. A good aquarium makes an effort to show natural local rock formations, gravel, driftwood etc., in accord with the general ecological niche associated with the display animals,
Back lighted legend boxes above the tanks should contain, at minimum, a picture of the animal, its distribution, habitat and any significant, distinguishing or peculiar characteristic.
An “intercom,” or some form of oral communication between the viewing and operations area would help simplify the tank maintenance and placement of display materials in the tank.
A handrail would keep the public slightly back from the display providing viewing for a greater number of visitors. It would also help reduce soiling or marking of the walls and glass by an enthusiastic audience. The public area should have a drinking fountain and rest rooms.
The purpose of the preceding suggestions was to cover all important aquarium design considerations in a general way. It seemed prudent to offer guidelines or limits rather than to suggest rigid specifications.
One of the reasons for having a public aquarium at Kainji was to help stimulate tourism. Undoubtedly there is an excellent variety of endemic aquatic animals which could be worked into a unique and enviable display. It could certainly complement the general tourism plan for the locality.
