If your fish are healthy adults and normally well fed, 5 days will not hurt them in the least. In fact, it may do them good - clean out the insides nicely.
If you do decide to have someone come in - or if there is ANY chance that someone may be there for any reason (not specifically even to feed the fish!)
HIDE all the fish food. Do not give anyone the opportunity to feel sorry for them and dump a whole bunch of food in the tank - fouling it.
I have fasted fish for up to 10 days with no problems. When the temperatures fall in the winter, the fish go dormant and fast for months. So.....do not feel badly about fasting them.