Koi and comets won't eat

[ponder]

Hello there!

Hope someone can help.  We have two pond tanks in our downstairs basement.  In the larger pond - about 350 gallons - we have two koi (5" - 6") and two comets (~3").  They've lived happily in there for many months .. and have always eaten well.

For the last couple of days, they have refused to eat.  They stay over in one of the corners of the pond, hiding under a plant.

We think they're terrified.  There have been some heavy machinery working on a new house being built next door - sometimes the vibrations are significant.  This has been going on (coincidently) for the past couple of days.

The second pond we have (around 300 gallons), located in the same room, sitting right next to the larger pond - has several smaller comets living in it.  They've been in that pond the same amount of time as the larger fish have been in the bigger interior pond.   These little guys are having no problems .. they're eating just as much as they always have and are swimming around happily.

Do you think the big fish are scared?  even though it doesn't seem to have impacted the smaller fish in any way?  Or .. could there be some other problem?

How long will the fish live without eating?  Any suggestions on what we can do?

We've tried all the usual routines ... we have always preceded the feedings with a tapping of the side of the pond .. it usually had them swimming quickly over to the feeding area ... we've tried running our fingers on the water ... (they used to kiss the finger tips) ... we've tried to get them out of the corner but they keep going back to it.

Thanks for any of your suggestions.

Cheers,
ponder

[saltydog]

Most fish can go a couple of weeks or more without eating.