The 23-year-old winger impressed Elefanti boss Rolando Maran enough to earn a move to the Stadio Angelo Massimino this summer, where he has been converted into an inside forward alongside Gonzalo Bergessio and Pablo Barrientos.
But Castro has yet to notch for the Sicilians, and was guilty of spurning several gilt-edged chances to do so in last weekend's 4-0 defeat to the Rossoblu.
He told ilcalciocatania.it: "I had a great opportunity to show what I can do but I didn't take it. I'm confident I will improve.
"We didn't profit from all the chances we created last Sunday, we played well for a long time but couldn't convert our quality into goals.
"Playing in a different position on the pitch isn't a problem, I played in a trident back in Argentina and did well.
"We're expecting a difficult game at the Massimino but the fans' support will be a big help. We're strong at home and our opposition know it.
"Parma have a lot of great individual players but their real strength is in the collective.
"All Italian teams are like that - they're tough to break down, and technically, tactically and physically strong."
Defenders Nicolas Spolli and Ciro Capuano are unavailable but midfielder Keko is hoping to prove his fitness in time to make Maran's 18.
Ducali strikers Dorlan Pabon and Ishak Belfodil are also suffering from a crisis of confidence in front of goal, with boss Roberto Donadoni eager to get them firing in a bid to earn a first win in five attempts.
Pabon impressed in pre-season after leaving Colombia but is yet to notch in Serie A, while ex-Lyon man Belfodil has failed to score for over a month.
He told Gazzetta.it: "I'm happy with what Pabon has done in terms of changing his movement but he needs to rediscover his eye for goal.
"It's a little bit different for Belfodil, he's been handy at putting pressure on the opposition but still has a lot to learn.
"If he can add more goals to his repertoire then he'll be very dangerous."
Injured winger Raffaele Palladino will stay behind but defender Fabiano Santacroce could make his first appearance of the season.
Ominously for Donadoni, Parma have never won at Catania in any competition.