A vibrant, hardy, beginner-friendly, reef safe, community, marine fish may sound like a contradiction in terms, but the royal gramma (Gramma loreto) manages to tick all these boxes and thus earns itself Fish of the Week this week. This small fish grows to around 8cm (3 inches) and can naturally be found in the tropical waters of the western Atlantic. Easily characterised by its vivid purple body, turning to bright gold before the tail, this fish makes its home in crevices and caves along rocky reef systems, and does not roam far from its home. If you’ve got a smaller marine tank, these stay-at-home fish could be perfect, but despite their peaceful nature, they will defend their home if another fish comes along to have a look (which is obviously more likely to occur more frequently in a smaller tank). For this reason, it’s best to keep these fish singularly, or as a breeding pair, as many other species do not inhabit ‘burrows’ in this way. Another curious quirk about this deep-water reef fish is its complete disregard for gravity. Rather than behaving ‘normally’ as we all know, the royal gramma will orientate itself to lie along its nearest surface, be that the floor, wall or ceiling of its cave, so it can be completely normal to see these fish upside down! Males and females can be difficult to distinguish between, but this fun, flamboyant fish will certainly catch your eye. What a fantastic fish for this week! Image courtesy of http://www.saltwatersmarts.com.