This reminds me of an issue we had when we lived in the country. A neighbor whose property was right behind ours leased space to bee keepers to put their bees there (I think they moved the bees from one place to the other during the year). But there was apparently no water close by for the bees, so they swarmed into MY yard (I had a couple of acres) and used my koi pond for drinking. It was a problem for me because the large number of bees actually brought the level of the pond down daily —it wasn’t a huge pond, just an ornamental pond with a water fall and 4 large koi. This meant I was constantly having to fill it up. Plus the fact that I’m allergic to bees and I had to wade thru them to do it. I just didn’t think that was my job, since my neighbors were making money to keep the bees on their property not me.
But lots of people are not good neighbors.
Doesn’t seem like a large problem. Keep your fish indoors for a year while ‘splainin’ to the neighbor and encouraging him to build his own pond. (If he is not engageable, build a bee killing trap.)