Spur, appearance.

1. Thorn. The catfish has only one main spine, while the fortune fish has many smaller spines in addition to the main spine.

2. Appearance. The catfish has a relatively large head, a distended abdomen, a flattened tail, a protruding cone-shaped mouth with four pairs of tiny whiskers, and no scales on its body, while the fortune fish has a small head, a long body, and fins on its back.