There’s an old Italian saying:

L’ospite è come il pesce: dopo tre giorni puzza

that dates back to Tito Maccio Plauto, 250 a.C. – 184 a.C..

In english it can be translated to “fish and visitors stink after three days”, a quote that for some reason is attributed to Benjamin Franklin, who was born 20 centuries after the saying was already popular in the “old world”.

Anyway!

When I say ideas are like fish, I mean that once you have an idea it looks like the greatest thing ever.

I apply this to ideas for new apps to build.

It’s going to be super popular!

Everyone will use my app!

It’s also applicable to new features:

I’m sure my users will find this a great new feature!

Give it 3 days. Let it sink.

After 3 days, the idea will smell like fish. You will see all its failures and defects.

You’ll have a much better perspective on it.