Former Betis coach Mel is a big fan of Castro and has been tipped to make a move for the forward in the summer.
"Of course I'll play with Betis in the Segunda (second division)," Castro said.
"I will stay at Betis, I'm staying here regardless.
"Although my salary will be reduced, I intend to stay. We haven't done things as well as we should, but we have to take care of this club."
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