iptables works for IPv4, but not IPv6.
ip6tables is the equivalent IPv6 firewall, and is installed with
iptables is for IPv4 connections,
ip6tables is for IPv6 connections. If you want your
iptables rules to also apply to IPv6, you have to add them to
ip6tables as well.
If you try and replicate your
iptables ruleset in
ip6tables, not all the rules that
iptables can do will port over neatly to
ip6tables, but most of them will.
Refer to the manpage for
ip6tables if you want to make sure the commands that you use in your
iptables will neatly port over.
If you'd like, we can help you create equivalent
ip6tables rulesets to match your
iptables rules, if you provide your firewall rules list (removing any information that could identify the system of coruse). Otherwise, we can only answer your general question.