Indeed, one of Cuba's national dishes -- with the wonderful name of 'ropa vieja,' or old clothes -- is a sort of shredded and stewed beef with a tomato-based sauce, served on rice.
Diaz works at a fishery plant in El Cotorro, 15 kilometers (10 miles) south of Havana, which breeds tilapia and catfish. They are also being raised in ponds and lagoons around the country.
The campaign is going pretty well, but production still needs to rise, he told AFP during a recent visit with foreign journalists.
He said Cuba is now producing 24,000 and 25,000 tons of the two kinds of fish per year.
Cuba's regular fishing fleet, by comparison, took in 24,500 tons in 2011, according to government figures.
Until 30 years ago Cuba had Latin America's biggest fishing fleet, one that operated in three oceans. But it was hit hard when the country signed an international fisheries convention in 1982 and the areas where the fleet could work were severely limited.
The coup de grace for the security of not going hungry was the collapse of the Soviet Union in 1991. The dismemberment of communist Cuba's main benefactor and supplier of fuel and other essentials triggered an economic crisis that brought Cuban industry to a standstill.
Today, Cuba imports 80 percent of the food it consumes ($1.6 billion worth in 2012), which is a huge burden for the government's meager coffers. So producing more food and importing less is a top priority for the government of President Raul Castro.
Food supplies have become more abundant in recent years but shops still tend to run short on some basics. Cuban families subsist in part on ration books that give them food at subsidized prices. But they do not live high off the hog by any means.
They can also buy food at regular supermarkets but have to pay much higher prices and do so in hard currency, which is tough when the average salary is equivalent to about $20 a month.
So the authorities are trying to boost production of food that is sold at subsidized prices.
Diaz said that in order to satisfy demand, production of freshwater fish should be "four, five or six times" what it is now.
But introducing Cubans to catfish, for instance, has not gone all that smoothly. Here, the creature has a reputation as being a predator. Comedians make jokes about it and a lot of people do not like the fish, which was introduced from Malaysia and Thailand in 1999 and 2000.
"People say catfish eat anything it runs into, so they turn their noses at it. Actually, it is a matter of having a bad reputation, more than anything," says Natalia Diaz, an industrial engineer. But she admits she has never eaten it at home.
But national TV anchor Agnes Becerra sings the fish's praises.
"Catfish is delicious, and my son loves it. There are people who say it does not taste good, but many of those who criticize it have not tried it even once," said Becerra.
Diaz says the fish does get bad press, but the real problem is that his compatriots just don't like fish, period.
"Cubans have no real habit of eating freshwater fish, or fish from the sea for that matter," he said. Nor do they eat fish during the pre-Easter period of Lent as do people in other Catholic countries of Latin America, he added.
And although production of freshwater fish is rising each year, there are no plans for now to export, because domestic needs are great and barely met, Diaz added.