A goldfish lover asked for an update about the goldfish in our water garden in containers:
Miniature Water Garden in a container is very interesting. It is not only for keeping few goldfish, but it can display water plants that help with the balance of the ecosystem. Water plants that grow totally immersed in water like for example Anacharis/Elodea (Egeria densa) is an excellent oxygenator for fish and it can help with filtering to achieve clear water. Other plants like for example water lilies can add beauty with the pretty flowers and floated foliage. Marginal water plants like for example the Japanese Sweet Flag Grass (Acorus gramineus) is small in size and it is very suitable for miniature water garden. Floating water plants like for example Duck Weeds (Lemna disperma) are enjoyed by goldfish to munch.
Wide containers that have some depth, with minimal 100 l water capacity is recommended. We use rainwater to avoid the need of chemicals (water ager) to eliminate chlorine in tap water which is harmful for gold fish. To keep water clear it is better to keep the amount of the gold fish and the feed to minimum. We use home made water filters that are made of plastic bottles with large mouth that are filled with gravels and plastic scorers (those for washing dishes). The filter is run by a small submersible water pump. Once a week, the filter can be cleaned and reusable.