Eight migrants were hospitalised early Thursday after a late-night brawl between Syrians and Afghans in the overcrowded migrant camp at the Greek port of Piraeus, authorities said.
A coastguard spokeswoman said the injured were only lightly hurt and were to be released later Thursday.
Scuffles frequently break out between migrants and refugees of various nationalities at Piraeus, and at the similarly dismal camp of Idomeni on the Greek border with Macedonia.
There are over 11,000 people at Idomeni and some 5,700 at Piraeus, waiting in vain for Balkan states to open their borders and permit them passage to wealthy northern Europe.
Desperation has spiked following an EU deal with Turkey earlier in March that foresees that tens of thousands of migrants not given asylum will be sent back to Turkey.
On Wednesday, hundreds of mainly Afghan migrants demonstrated in Athens to demand the reopening of borders, which have been closed since the beginning of the month.
There are over 51,000 people trapped in Greece and hundreds continue to arrive, despite the deal with Turkey on limiting the influx nominally taking effect on March 20.