The warm waters of the Sea of Galilee allow a variety of flora and fauna to thrive, which have supported a significant commercial fishery for over two millennia. Local flora includes a variety of reeds along most of the shoreline as well as Phytoplankton. Fauna includes Zooplankton and Benthos, as well as a fish population which notably includes Tilapia (locally known as St. Peter’s Fish). (from Wiki)
Looks like it probably would have been tilapia. The traditional site of the miracle of the loaves and fishes is in an area called Tabgha, on the northwest coast of the Sea of Galilee.

A fish called Wanda - I'm sorry I just couldn't resist.(In case you don't know that's the title of an old movie.) I have a friend who lives in the hills above the sea of Galilee I'll email him, Mike will know.

It was not documented so any answers you will get are speculative and based on personal belief, same as mine.

There was no single fish that fed 5000 people. It was a symbol not meant to be taken literally like so many other stories in the bible.

What I believe happened was Jesus' love and influence was so great that people for that particular event took out and shared their rations that they had selfishly kept hidden away.

So Jesus did feed a huge amount of people. That is why he was so good. The miracle was that he got people to forget about being selfish and share with their neighbours.

The spiritual truth is that He performed the miracle, and that 5000 were fed. The name of the fish is meaningless.

he fed them Sea Bass ... Plain and Simple.

Do you want to know the variety of the wine he produced at the wedding in Cana too? Does it really matter? I would like to know answers to lots of things but they may not be recorded or documented so I will never know.

There is no evidence that this event ever happened. Only the Christian bible has reported it, and it has no more credibility than any other religious myth. Most of the New Testament was composed a century after Jesus was killed.