I have a tiny 3 gallon at work with teeeny-weeny little ember tetras and microrasbora kubotai. All under one inch. Can these little guys survive for 4 days without food while I'm not in the office?
Even for little fish like that, 4 days is almost nothing. In the wild, fish easily go 7 or more days without food. In the wild, fish don't get fed anywhere near every day.
Quite a few members leave their fish unfed for a week or more while on vacation. I have done it on at least 2 occasions. You should not have any problems related to food.
Apparently Adult fish can go for 2 weeks without food. Im with family at the moment for the holidays, and leaving my 3 tanks for 8 days. Ive done it before with no problems. I feed as normal on the day I leavin with just a small bit more than usual. Ive 2 adult tank and one fry tank, and often enuf i need to be away for a couple of days.
I once lost 10 fish after being gone for a week, but this had no connection to food, my heater had broken while i was away and the fish that depended more on the heat died. And even with that, the other 10 or so fish in the tank at the time survived and are still goin strong
i really dont think 4 days will be a prob.
Actually not feeding over an extended absense helps keep waste production down too so if a filter does happen to malfunction, there will be less ammonia buildup.