Fish Care: Solving Common Pond Fish Problems

Fish Care – Problem Solving

“If I have a very sick fish, which is the most humane way to kill it?”

Many pond owners are squeamish about euthanasia, but it’s a responsibility. The safest method: hold the fish firmly in a dry cloth and deliver a sharp blow to the head—death is instantaneous. A veterinarian can also over-anaesthetize.

“I have a large goldfish that appears very swollen and distressed. What could be wrong?”

A distended goldfish may be spawn-bound (female). Sometimes the body prepares for breeding, conditions change, and eggs are reabsorbed. If unsuccessful (due to undernourishment or stress), eggs harden, cannot be expelled, decay, and gas accumulates, leading to death. Gentle abdominal massage in wet hands sometimes helps, but often the fish dies. Prevention via a healthy environment is best.

Another cause: dropsy (bacterial). Scales protrude, resembling a pine cone. Salt bath (25 g rock salt per 4.5 L water) plus proprietary antibacterial remedy may work.

One-sided swelling could be a tumor—no cure, but the fish may live years.

“My beautiful fantail goldfish swims alternately on its back and nose-down, sometimes spiraling drunkenly to the bottom. What causes this loss of balance?”

Common in fancy goldfish: swim bladder derangement. Usually caused by sudden water temperature change—stress on introduction, large water change, or clear frosty weather. Steady temperature usually controls it, though symptoms may recur with further shocks. Unsuitable diet can cause temporary similar symptoms after feeding; use quality flake or stick food.

“How can I deter a heron? It visits my small pond regularly, but I’m reluctant to net the pool as it spoils the plants.”

Herons target even urban ponds. Netting works but detracts from beauty and complicates maintenance. Provide hiding places: a flat stone on supports where fish can refuge, arranged unobtrusively. Otherwise, erect short stakes 30 cm (12 in) from the pond edge, projecting 15 cm (6 in), with a strand of fishing line. Herons walk in to fish; their sensitive legs touch the line, deterring them.

“When fish die in a pond, do they always come to the surface?”

Mostly yes. If you haven’t seen a fish for a week or two, it’s likely hiding among plants (especially in spring and autumn). Dead fish only fail to surface if entangled in submerged plants, which may cause minor pollution unless death was from disease.