You could use join:

print join ", ", @nickArray;
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That prints all the elements of @nickArray separated by a comma and a space. Or, you could set $, (output field seperator) to ", ":

$, = ", ";
print @nickArray;
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If you use that, you're better off localising the effect of $,:

{
    local $, = ", ";
    print @nickArray;
}
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See perlvar for more on $,.