Setting up an outdoor aquarium

This spring an outdoor aquarium has provided quite literally hours of entertainment as we have been able to watch the development and metamorphosis of pond-life right in front of our noses.
The experiment began with the purchase of a tank. Almost anything will do. In the end I bought a small starter tank from a local pet shop, though now I’m on the look out for something larger and I’m sure second-hand or home-made will be fine.
Filling the tank was the next task, so armed with a lidded bucket I headed for a local pond back in March and came home with a good quantity of rather cloudy water, the pond having been disturbed by recent heavy rain.
Over the ensuing days the water gradually settled out to leave a good centimetre of sediment in the base. The water was also full of life. Tiny water fleas, fly larvae and other microscopic ameoba started to become apparent, suspended in the water or roaming the sediment at the base. We dropped in some stones, an apple tree branch and a bit of weed to provide some oxygenation and left it alone. In retrospect this was an important stage as it allowed populations of the lower life-forms to establish and provided a base for later introductions.

Stage two was the collection of specimens so we made a return to the same pond at the end of April. The pond was teeming with tiny wriggling black tadpoles and one swoop of the net brought a hundred or more into the bucket. We came home with twenty or so, as well as a caddice fly larvae, complete with its portable home – the jewel in our pond-dipping crown and a greater waterboatmen who has previously appeared on this blog.
Carefully released into the tank, the newly arrived creatures quickly appeared at home, the tadpoles feeding on the algae that was forming on the glass or the leaves of the pondweed that was now starting to sprout roots.
And so our stage was set. The tank sat on a chair on the patio, partly in shade. A stool quickly found a permanent home in front of it and after a day in the office the aquarium was the first port of call when returning home, to see what had developed during that day. The Caddice fly larvae marched regularly around the tank, initially apparently hanging on for dear life until it’s floating equilibrium became reset after it’s brief time in the air whilst leaving the pond. The tadpoles continued to munch on algae, sucker mouths like lampreys rasping repeatedly at the glass, the first vestiges of back legs slowly appearing across the population.

No further maintenance has been needed, bar topping up with harvested rainwater after a few warm days had reduced the water levels. A fine pond weed did require some removal in the latter stages of tadpole development, but more on that in a later post. That aside, the tank had become a fascinating, life-sustaining environment over these past few weeks and is an experiment I look forward to repeating.
Water flea

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