In a short time, after hanging petunias and clematis above my pond, 6 goldfish died. These plants are poisonous, but also when they hang above the water? The water parameters are good.
Answer
Dear Jane,
The only connection there could be between those Petunias and the fish mortality in your pond is that possibly the seeping irrigation water from the pots ends up in the pond, which causes more fertilizers in the pond water.
During hot and sunny summer days, a pond that is heavily enriched with fertilizers can develop a bloom of microscopic algae (usually cyanobacteria) floating in the water. During the day they do photosynthesis and multiply very quickly. At night, however, only respiration continues, so that the abundance of organisms in the water can drastically reduce the oxygen content, which can lead to an oxygen deficiency for larger animals that live in the water, such as fish. Such an oxygen deficiency can quickly arise, especially in small ponds.
You can prevent this by using a good filter and by planting sufficient water plants in the pond.
There does not necessarily have to be a connection between those plants and the fish mortality in your pond.
Answered by
drs. Marc Reynders
Biology, systematics and evolution of seed plants. Specialized in tropical Cyperaceae.
http://www.ugent.be
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