"My heart danced when I saw this extraordinary group of fish," al-Najjar told Anadolu Agency.
But an Israeli military vessel soon approached, scattering the fish before al-Najjar had lifted the catch.
"They ordered me to go back without giving me a chance to point out that I was still in the permitted fishing zone," he said.
The episode, which he said happened two weeks ago, ended with al-Najjar losing his catch and his 15-year-old son suffering severe back pain after Israeli troops aboard the navy vessel blasted their little fiberglass boat with a water-cannon.
Over the years, Israel has gradually reduced to only three nautical miles from the Gaza coast the space allotted to Palestinian fishermen.
Following a ceasefire that ended eight days of cross-border fighting with Hamas in late 2012, Israel had increased the fishing zone to six nautical miles.
Jamal Bakir immediately invested $40,000 in his fishing trawler – buying an electric generator, strong lamps and new netting and gear – in hopes of benefiting from the new situation.
In the first few months after the ceasefire, he and his 22-man crew did good business.
But he soon found that Israeli restrictions on fishing space were not the only obstacles facing the roughly 4,000 fishermen working in the tiny coastal enclave, which is hemmed in by Israel and Egypt on three sides and the Mediterranean Sea on the fourth.
An ongoing Egyptian army crackdown on tunnels beneath Gaza's southern border with the Sinai Peninsula has effectively severed the lifeline that had provided Gaza's nearly 2 million inhabitants with many vital goods, including affordable fuel.
Now, Bakir is forced to buy Israeli fuel for 7 Israeli shekels per liter, up from 3 shekels per liter of Egyptian diesel.
"We had been trying to improve our situation, but now we're suffering once again," he told AA, watching as his employees returned from yet another unprofitable voyage.
"It costs us 6,000 shekels (roughly $1,700) for fuel, when our total catch sells for about 2,000 shekels," Bakir said.
"We've become bankrupt; we're unable to repay the loan," he lamented.
Nezzar Ayyash, head of the Gaza fishermen's union, said that 80 percent of those working in Gaza's fishing industry had been rendered jobless due to both the Israeli restrictions and the dearth of cheaper Egyptian diesel.
Among those who have given up on fishing for now is Hazem Meqdad, a 40-year-old father of four.
When Palestinian fishing boats were allowed to sail up to 12 nautical miles from the Gaza coast, Meqdad used to earn between 500 and 1,000 shekels (from $140 to $280) a day.
As Israel gradually reduced the fishing zone, however, Meqdad's income declined.
Scarce – and therefore more expensive – fuel imported from Israel has complicated his fishing trips; most times he set sail he returned empty-handed.
"These days, there was no fuel and no fish," Meqdad told AA as he worked at his temporary job repairing fishing gear.
He landed the job through a program run by an international aid organization that aims to support Gaza fishermen.
Meqdad now earns 60 shekels (roughly $17) per day at this two-month job – barely enough to buy food and basic household items for his family.
"I'm working through this temporary program despite the humiliating conditions because I simply won't make 60 shekels if I worked independently, as I used to do."