ahah, someone mentioned herons, this can summon 'the heron file' compiled from various ponders experience, over the years....

Herons have a muddle of habits, some go in for neat extermination jobs, others may be picky, leaving the whole body of a fish and only eating the tail section. Go round a lake after herons have been and you will find a lot of variation in kill habits... Yes, they will fly around and around a location on many days before even landing on a tall tree close, for a more careful look... Very keen eyesight and hearing

After a serious heron attack, its normal for fish to go hiding for weeks, so you never know what has happened.... on a well planted pond with a lot of cover, most fish survive though you will notice the dramatic difference in their usual behaviour and wonder why.

Here's a few notes collected from observations and other folks experience

1) Predator nets.... cheaper than losing koi, downside, local animals can get trapped in it, snared. Not very pleasant explaining to your neighbor why their pedigree cat or dog lost its life or leg through strangulation. Predator nets are probably the most cost effective barrier method, a large mesh of around 4" should allow most varieties of plants to grow through it without tangling the mesh. Smaller meshes tend to be a mess with plants, strangled pets, and dead frogs by the time Spring arrives...

2) Barrier method.... Suspend strong fish line taut, at a height of 12" over and around the pond, herons hate trip wires. An elegantly simple way to baffle a dim fishbag on stilts, it often works, many folk have reported seeing herons 'baffled' this way.... a near invisible line that they can't see, bump into, cannot step over without tripping, is enough to stop them.... I guess herons have yet to master the skill to sneak along the ground without the use of their long leggedy stilts...

3) Hiding places... Step up cover within the pond... water lilies.... big bits of pipe, float large sheets of black polythene (trash bags will do) trippy stuff for tangling up predators... hiding places for fish. Surprisingly, many black plastic objects, when submersed become virtually invisible, in a natural setting, so the idea of this clutter in pond is not as bad as it sounds.

I like this method, it creates a lot of hiding places and is virtually invisible to the usually attractive pond setting, it makes it very difficult for the likes of persistent herons and raccoons when they raid.... useful in winter when foliage is bare and fish want somewhere quiet, to hibernate. Bare crystal clear ponds must be an easy target for predators, the garish and brightly coloured fish must just shout loud and clear, 'sushi bar' to every itinerant fish eating scoundrel passing within sight overhead.

4) Pond design... When you make a pond, make 45° sides, herons have gangly legs, they like 'easy walking' conditions, they hate 'trippy' pond surroundings... The one common weakness of predatory birds is the vulnerability of their gangly long legs, they absolutely rely on an easy landing place, and an easy stroll into the pond, handy shallow terraces are a big help....

5) Trapping... I can't be so fiendish, I cant advise you put out snares... a simple loop of fish line can lock onto a predators leg. Nasty way to die, that

6) Shooting... Not everyone in the world live in areas where herons are protected, or rare... I can't recommend a .22 air rifle, a bit politically incorrect, even though a heron is easy to hit at 200' with a decent scope, unfair, too easy I guess. Anyone who has used a rifle properly could hit a quarter at 100 feet so for the squeamish, clipping some tail feathers is possible .....or hit a bucket placed beside the pond loud and close enough to frighten the bejasus out of the vile fish bag... that is an effective clean way....Alas rifles in most peoples hands are counter productive, you can waste a lot of time waiting for the opportunity to use it, to learn how to be competent with a rifle and the consequences of a bad tempered person with a lethal tool is well, unpopular...

(Continued in part two)
regards, andy
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