Still not sure what too long would be? We had some early cold and I don't think I have fed the gang since first or second week of November. The weather forecast for metro-Detroit calls for cold weather another two weeks?
So that means almost no food for 6 months......Except for pond algae.....I know Larry mentioned my logic is reverse. But I think with smaller koi algae could supplement its energy needs better compared to larger koi. A larger koi who would require more algae fuel to maintain safe late winter/early spring health. I have always understood that larger koi have the extra fat reserves, but I think the little koi have one advantage based on algae keeping them going longer in early spring. Less requirements mean less fuel to keep the koi body going.
Yes, I have experienced this before and have seen some koi really struggle towards the end of winter.....
This is one reason I don't like to add large koi to my pond...The reason being if they have spent 2 to 3 years in a warm climate and then I put them in my Michigan pond I fear for their winter tolerance........Although it seems the most important factor is ALWAYS genes.....