BART VAN DIJK: MEET AN AQUARIST SERIES by Howard Norfolk

Jimmy “Carter” did not drive a truck, and Margaret “Thatcher” was not a roofer, but Bart “of the Dyke” certainly has lived up to the name of his Dutch ancestors! He recently retired from a career in water related construction, travelling to various sites in North and Central America as an inspector on projects connected with dredging, land reclamation, wharves, ports, breakwaters, coal terminals and marinas. He now lives in a small suburban house with his wife Anne, and his activities still revolve around water, but on a much smaller scale: that of his home aquariums.

Bart with his 150 gallon plant tank

Bart has been keeping fish for fifty years, starting as a young man in Holland. For a long time he had just one tank due to pressure of work and family. More were added here and there over the years, and even more since his retirement, so that now he has seventeen tanks, one in his living room and the rest in his basement. His interests are diverse, and he has not specialised in any one aspect of fishkeeping. Rather, he likes to try a little of everything – “that’s the fun of it”, and takes a somewhat scientific approach, experimenting with his own ideas and trying to improve on those of others. Bart’s interests, and therefore the contents of his tanks, change from month to month and year to year, but right now they are as follows:

The 40 gallon tank in the living room used to be a heavily planted community tank but now contains a pair of discus, which Bart is attempting to breed. They have eaten their first three batches of eggs, but it is hoped they will have a successful hatch soon.

Bart enjoys finding ways to breed difficult fish, and has bred many species over the years. For instance, he is proud to have bred flying foxes, finding that adding killifish to their tank triggered the spawning.

He has also bred Congo tetras. In their case he tried many things to trigger them; increasing the lighting, changing water temperature, changing water qualities, and even creating “lightning storms” using both light and sound. But their spawning was a surprise to him - it happened when he was away on a week’s camping trip without doing anything to encourage them !

Golden Severums

A long term interest of Bart’s is a group of golden severums he keeps in an old wood framed 80 gallon tank. He has had these for twelve years, and they have bred several times, producing 200-400 fry at a time. He is able to sell the young ones to local pet stores. This tank has four zones of different lighting intensity: Bart wanted to see if the fish preferred to spend their time under any particular type of light. (They didn’t ).

Koi

In the centre of Bart’s fish room is a large square tank of about 150 gallons. Bart took a welding course in connection with his work and had to make something, so he made this tank and its metal stand. Bart is interested in aquatic plants (he is a member of his local aquatic plant club), and this large tank contains his main collection of plants, including some hard to grow species. As part of his ongoing experimentation, different areas of this tank are filtered in different ways and have different substrates, so that Bart can see which conditions plants like best. It is lit with four 1” tubes and two 1½” tubes, which are lined up in a row, descending from 6500K to 4000K.

Nothobranchius rachovii (Killifish)

Another large tank holds half a dozen koi. They are two years old and measure 15” to 20”each. Bart is helping and advising a friend who has started a koi farm. They want to find the most efficient filter system to keep the largest number of fish in the smallest body of water. Bart’s under-gravel filter in this tank became clogged after one year and bacterial problems developed, so Bart made his own three stage external filter. Air is added to the water between each stage.

They also want fast growth. Bart reckons that a maintenance diet is 1% of a koi’s weight in food per day, but they can eat as much as 4%. Bart feeds his 2% of their body weight per day, and finds that they double in weight every 28 days! He uses Pro-Form pellets in the morning, and frozen bloodworms or beef heart at night. He also gives them plant material from his other tanks.

Bart is considering building a pond this year, and is researching filter systems for this, since he wants to do it right the first time. Meanwhile he grows water plants outside in containers each summer, and brings them indoors for their dormant winter period.

Bart is a member of the local Killie Club and has seven tanks of killifish, which he is breeding. He keeps a detailed daily written log of their activities.

He also has a large tank full of Endlers livebearers, and has just started attempting to breed angelfish in another tank.

Killifish tanks

Bart’s community fish are now in an octagonal tank, and include cardinals, harlequins, rummy noses, neon rainbows, and quite a few female bettas, which he bought because he read that they might eat the hydra which are infesting a couple of tanks. (They didn’t).

That wraps up the list of Bart’s pets, unless you count the stick insects! He inherited a pair from his grandchildren, put them in a home made octagonal tank in the dining room, and now has about eighty of them!

Stick insects are not the only bugs Bart breeds. He produces many types of live fish food: infusoria cultures, wingless fruit flies, microworms, grindal worms, and white worms, and collects earthworms from his compost container. He raises brine shrimp in an ingenious hatchery he built himself, and also makes batches of beef heart food, with which he experiments by adding different ingredients.

One of Bart’s ongoing interests is the scientific study of water conditions and their effects on plants and fish, and he regularly writes articles on this subject for aquarium clubs’ newsletters. He has every imaginable kind of water testing kit, which he actually uses. Last year he conducted a major experiment on plant fertilisers and hydroponic gardening. He has a microscope, which comes in useful particularly for his investigations into fish diseases.

Bart uses the Internet, and prints out reams of articles on many topics, which he keeps neatly in folders. An advantage he has over most of us is that he can read the Dutch articles as well!

View some well crafted articles written by Bart in Aquarticles' Aquarium Management/"Buffers" and Breeding/"Triggers" ..."Finding the Triggers"... "Copper in Your Water?"and "If Angels Could Talk".