Fish Leaping and Chasing in Spring: Spawning, Stress, or Parasites?

3x4.5 m pond, 1 m deep, 2 goldfish, 2 koi, 1 shubunkin, 2 tench + fry. Frogs mating, cats watching. Fish leap, chase, twist. Filter cable cut. Owner asks if normal.

Interpretation

• Chasing + twisting leaps: Likely spawning behavior (spring, temp rise).
• Flashing (rubbing): Would indicate parasites.
• Hiding at depth: Fear of predators (cats, herons, frogs).

Follow-Up: Fry Deaths & Grey Bloom

Tench fry dying with grey fuzz = fungal (Saprolegnia). Common in fry; most die anyway. Separate fry, use antifungal, feed fry food.

Immediate Needs

• Repair filter cable (safety + filtration).
• Test ammonia, nitrite, nitrate.
• Net frog eggs if overpopulation feared.
• Consider pond netting for herons/cats.

Leaping in spring is often spawning. Fry losses are normal. Fix the filter.