列出每个类别的自定义分类项目

Question

I seek some help listing all post titles per custom taxonomy category. It's a taxonomy registered to native wordpress pages.

Please check below what I tried so far:

My Taxonomy adding code:

function create_topics_hierarchical_taxonomy() {

  $labels = array(
    'name' => _x( 'alltanks', 'taxonomy general name' ),
    'singular_name' => _x( 'Tank Category', 'taxonomy singular name' ),
    'search_items' =>  __( 'Search Tank Categories' ),
    'all_items' => __( 'All Tank Categories' ),
    'parent_item' => __( 'Parent Tank Category' ),
    'parent_item_colon' => __( 'Parent Tank Category:' ),
    'edit_item' => __( 'Edit Tank Category' ), 
    'update_item' => __( 'Update Tank Category' ),
    'add_new_item' => __( 'Add New Tank Category' ),
    'new_item_name' => __( 'New Tank Category Name' ),
    'menu_name' => __( 'Tank Categories' ),
  );    

  register_taxonomy('tanks',array('page'), array(
    'hierarchical' => true,
    'labels' => $labels,
    'show_ui' => true,
    'show_admin_column' => true,
    'query_var' => true
    //'rewrite' => array( 'slug' => 'tankcategory' ),
  ));

}

Query posts:

<?php
           $args = array(
            'post_type' => 'post', // or should it be page?
            'posts_per_page' => '1',
            'order_by' => 'date',
            'order' => 'DESC', 
                'tax_query' => array(
                    array(
                        'taxonomy' => 'alltanks',
                        'field' => 'slug',
                        'cat' => 49
                )
            );
            $query = new WP_Query( $args );
           ?>
           <?php if (have_posts()) : while( $query->have_posts() ) : $query->the_post(); ?>