Setting up a reef aquarium may involve more inhabitants than you bargained for. Chris Sergeant looks at the good, the bad, and the ugly visitors you might meet.
CHRIS SERGEANT Chris works in conservation research and is a strident aquarium journalist.
A HITCHHIKERS GUIDE TO THE
ONE OF THE most enjoyable aspects of setting up a new reef tank has to be rock-watching. Once your tank is filled and the pumps switched on, it’s time to sit back and enjoy your handywork. It’s easy to assume that your tank is empty, but just because you haven’t intentionally added any livestock, it doesn’t mean that life doesn’t exist. Your live rock structures are often a bustling metropolis of micro-organisms.
It’s not just microscopic fauna that’s likely to have hitched a lift, and there is almost certainly a vast ensemble of invertebrate life waiting to emerge and investigate tits new home. While many will be beneficial and should be welcomed with open arms, there are others with more sinister designs.
Spongebob’s home
Some of the most obvious are the sessile inhabitants. Sponges encrusting over the rockwork are easy to spot, decked in a variety of yellows, oranges and whites. Being filter-feeders, physiologically speaking, sponges are like a hollow, perforated sack, using self-generated currents to draw water through their pores into a central cavity, the spongocoel, where suspended food particles are extracted.
Hitchhiking sponges are generally harmless in a reef aquarium, but some larger species can engage in chemical warfare with corals, releasing toxic compounds into the water. Some of the most commonly encountered are the ball sponges and calcareous Scypha sponges, with the pineapple sponge making a regular appearance. These tubular-shaped sponges prefer low-light conditions and thrive in high nutrient areas with elevated silicates. If your population eventually proliferates, it’s worth reviewing your feeding regime to ensure the tank isn’t being overfed, and keep an eye on your phosphorous levels, as elevated readings can be an indication of increased silicates. In the wild, angelfish browse on sponges, but an easier option is to simply remove them with a pair of tweezers.
Similar in appearance are tunicates. Although visually less porous than sponges, they function in the same manner, drawing water into their body cavity, or pharynx, via their oral siphon. Despite appearing to be as far-removed as probably possible from humans, tunicates are actually members of the same phylum, Chordata, as we are. The sessile adults may lack any for
