Hi Cris

The fishing times are guides only. Other variables come into it also.

Were you land based or in a boat? Did you stay in the one location for those 4 days or did you try different spots? Did you match the hatch (use bait that the fish are eating at the time)? Were you targeting a particular fish or just after whatever happens to be there? etc, etc.

For example, if you were land based did you try different casting lengths? 90% of land based anglers cast over the top of the fish they are trying to catch. Or another example, did you try different baits or lures or did you stick to the one bait?

See, so many variables come into it.

Maybe if you gives us more detailed info as to what you tried and used, someone from your area might be able to give some tips for next time.

Funny how you get those days. Everything looks great, all the stars are aligned and still no fish.
I don't think it's because of global warming 😊 Could be a number of other factors like itsabout said.

The other day I went to my favourite fishing spot with the same frustrating zero results. 
Afterwards I found out that somebody was illegally trawling in the area and afterwards most fish were gone.
Took quite some time for the spot to produce again.
There could be many other unforeseen factors. Maybe a group of predators hunting in the area or some unusual currents, etc.

Are you usually fishing the same waters with good results, or are you new to fishing in this area?

Cheers

Maybe someone else was fishing in that area too that can offer some feedback.

The bait you were using might be a clue here... Sardines usually stay in schools and move on. 4 days is a long time in the life of a sardine. Were you fishing in the same area where you got the sardines?

When I use live bait, I always get the bait right where I am fishing. I never get live bait and then move to another location. It is all about matching the hatch.

It sounds to me as though you left the target fish behind. Any fish feeding on those sardines would be staying near the sardine school.

Fishes, whatever size and depth in the water column, will not take to bait of any type if the water temperature is cold in the tropics. They get lethargic and too lazy to expand their energy to chase bait. Sometimes they even wait until the ideal feeding current starts. Some exceptional are Stingrays, Sharks and Sea Catfish. Ask any qualified boat Captain.