Disappearing Goldfishes

Most of my goldfishes disappeared from my outdoor pond.  I have covered it with plastic fencing.  There are a few gaps but not big enough for kingfishers to go after.  So for some times my fishes were ok.  They are growing big.  I usually buy "food" goldfishes as they are cheap and when they are big, they do look just as good.  However, after my Japan trip, I noticed all the food are floating for a long time.  I took a closer look and they have all disappeared!   I have no idea what else other than kingfishers can eat my goldfishes.  B3 suspected that it may be a black cat who was lurking around our front yard.  One of our neighbours told him the black cat has been eating up her fishes in her pond.

I bought 1 in square metal fencing and cover the pond totally.  This morning, I bought more fishes and put them in the pond.  Let's see if they disappears again.

I am also thinking about keeping a silver arowana.  It is cheaper to buy.  However, I had put in three or four before and they all jumped out of the pond and died.  Now with the metal fence cover, maybe I could try again.  However, it is an expensive hobby as I will have to buy food fishes or frogs regularly. 
Maybe I will rear some fighting fish instead.  I am still mulling over all the different fishes I can keep in my pond.