use strict;
use warnings;
use XML::Simple;

my $xml_raw = <<XML_RAW;
<survey>
...
</survey>
XML_RAW

my $data = XMLin($xml_raw, ForceArray => [qw(river fish)], KeyAttr => []);

foreach my $Animal (@{$data->{animals}{fish}}) {
	print <<"*END*";
[ Survey information for: $Animal->{name} ]:

Saltwater:$Animal->{saltwater}
Freshwater:$Animal->{freshwater}
Rivers covered in survey:

*END*
	for (@{$Animal->{river}}) {
		print $_, "\n";
	}
	print "\n";
}

##</code><code>##

use strict;
use warnings;
use XML::Rules;

my $xml_raw = <<XML_RAW;
<survey>
...
</survey>
XML_RAW

my $parser = XML::Rules->new(
	stripspaces => 7,
	rules => {
		_default => '',
		river => 'content array',
		fish => sub {
			print <<"*END*";
[ Survey information for: $_[1]->{name} ]:

Saltwater:$_[1]->{saltwater}
Freshwater:$_[1]->{freshwater}
Rivers covered in survey:

*END*
			for (@{$_[1]->{river}}) {
				print $_, "\n";
			}
			print "\n";
		},
	}
);
$parser->parse($xml_raw);

##</code><code>##

my $parser = XML::Rules->new(
	stripspaces => 7,
	rules => {
		_default => '',
		river => sub {'.river' => "$_[1]->{_content}\n"},
		fish => sub {
			print <<"*END*";
[ Survey information for: $_[1]->{name} ]:

Saltwater:$_[1]->{saltwater}
Freshwater:$_[1]->{freshwater}
Rivers covered in survey:

$_[1]->{river}
*END*
		},
	}
);
$parser->parse($xml_raw);