sera guide - Marine aquariums

Invertebrates Good maintenance provided, invertebrate diseases rarely occur. You should neverthe- less consider certain precautions. The skeleton formation of stony corals is af- fected if the water temperature exceeds 30°C (86°F). Furthermore, the symbiotic al- gae living in the coral tissues (zooxanthellae) die, and consequently also the coral itself will die. Crustaceans shed their skin regularly. The water must contain approximately 400 – 450 mg/l (ppm) calcium for them to build up a new exoskeleton; the carbonate hardness must be between 8 – 10°dKH. If an invertebrate becomes stunted despite best possible maintenance conditions, the animal must be examined for external para- sites. Those parasites may be very small and possibly only come out at night. The animals should be fed sera crabs natural and sera shrimps natural as to prevent deformations while shedding their skin. Planarians are flat white or red worms sized approximately 5 mm. They can harm ane- mones, corals, etc., with their excreted slime. The worms can be siphoned out of the aquarium by means of a flexible hose. Some- times it is useful to place a strong torch above the aquarium at night, since many pla- narians assemble in the light and then are easier to remove. Check invertebrates thor- oughly before buying them! Small, brownish- red, oval spots are usually planarians. Although bristle worms (Polychaetes) are actually debris eaters, they eventually nibble on mushroom anemones and stony corals. Furthermore, they tear at their prey and injure the animal with their sharp jaws. It is possible to attract them with fish meat, then catch and remove them. As they are mainly active at night, this procedure should be carried out in the dark. Be careful: Do not touch these worms. The bristles break off and may cause skin inflammations! Small bristle worms hide in the gravel during daytime and can be removed by siphoning off a large quantity of the substrate (approx- imately 30 – 50%) and washing it with fresh- water. Usually, this is sufficient to remove bristle worms from time to time. 11. What to do in case an animal gets ill 56 Many snails nibble on sea anemones, corals, etc. In a reef aquarium, every snail should be carefully removed by means of a pair of tweezers. Some snails exclusively feed on sessile invertebrates.