From Openwaterpediaprofessional marathon swimmer from Italy and a swimming coach with G.S. Fiamme Oro. He was a distance freestyler in the pool.
He is considered one of pioneers of open water swimming in Italy. He has participated as a swimmer and coach for more than 10 years on the Italian national swimming program.
Castellano participated 7 times in the 33 km Maratona del Golfo Capri-Napoli and competed in the FINA World Cup in 1990. He participated 25 km FINA World Cup races in Ismailia , Port Said and Nilo in Egypt and in the European Swimming Championships twice. He finished third in a 30 km Mediterranean Sea swim in Greece in 1993 and in two marathon swims in Bahia, Brazil in 1989 and 1990. He won the Italian 25 km Open Water Swimming Championship 5 times.