Did you know there are actually quite a few popular marine invertebrates, that should NOT be kept in your reef tank???
The majority of invertebrates that should be avoided for marine aquariums are heterotrophic; that is they cannot manufacture their food and are not partly or mostly photosynthetic (can manufacture food from light so are autotropic) like many marine inverts we keep. A specialised feeding regime is required to keep these species alive and is very difficult to provide. This usually means culturing the organisms they eat (like zooplankton, rotifers, copepods) and target feeding them
Other invertebrates to be avoided have extremely short life spans or are quite toxic to you and their tank mates.
Think twice about getting the following marine invertebrates:
1. Jellyfish: Jellyfish are cool, there’s no question about it, but they need to be kept suspended in the water column so require a specialised circular water flow system called a Kreisel.
2. Sponges (Porifera): most sponges are heterotrophic (but there are a few photosynthetic sponges around which can be ok for marine tanks) so require specialised feeding, filtering out of the water plankton and bacteria. Sponges often don’t do well in aquariums because they need a lot of silicates in the water. Many sponges can also release toxins into the water.
3. Sea Apples (Pseudocolochirus species): these weird and extremely colourful invertebrates are prone to dieing because they do not receive enough food. Unfortunately when they die they will kill everything else in the tank with the toxins it releases, not a good sort of apple…
4. Octopuses and Cuttlefish (Cephalopods): Even though these are very cool creatures to keep they mostly only live 1 year, will eat most of your tank, octopuses are difficult to house because they can usually escape the tank not matter what you do to stop them!
5. Nudibranchs and Sea slugs: These invertebrates live short lifes and many have species specific dietary requirements (for example only eating one kind of algae or animal). Add to the equation that many release metabolites when they die that will screw up your water quality.
6. Sea Pens (Cavernularia species): Sea Pens are also heterotrophic and require a specific diet fed to them, they also require about half their body length of substrate to busy into, which usually means about 20 cm of substrate beneath them, can you provide that?
7. Large hermit crabs (Dardanus species): Active, hungry and destructive these hermit crabs will happily knock things over, rip up corals/inverts/sleeping fish and mess the tank up; not a good look.
8. Carpet anemones: these often do not do well in captivity. Any anemone has the potential to roam around the tank, climbing over corals to get to a good position they like. Some species will enter into toxic stinging matches with (mostly) soft corals.
9. Heterotrophic corals: stunning coloured corals like Sun corals (Tubastrea species), Carnation/Strawberry/Cauliflower corals (Stereonephthya, Scleronephthya, Dendronephthya, Siphonogorgia species), Lace corals (Stylaster and Distichopora species) have no photosynthetic zooanthellae so must be target fed plankton correctly and often. Unfortunately this means most waste away and eventually die in home aquariums. Some also have specific water quality requirements, which are hard to meet. Many also require extreme water movement to be happy as well.
10. Goniopora coral species: This is one of the most important species but is one of the shortest lived. Most don’t last a year in captivity. These popular corals do have zooanthellae but just don’t last in aquariums without wasting away within the year, it is thought that maybe they have specialised supplementary feeding requirements of specific plankton in the wild.
All the above examples of species to avoid in saltwater aquariums of course have exceptions to the rule; generally this success is a result of really optimising the tank environment to suit the particular species. I have Facebook friends who have successfully kept a tank load of Moorish Idols.
So if you really have you heart set on one of the above, don’t let me put you off, do your homework and go for it! I would love to know how you get on too. This hobby is always changing and improving, 30 years ago they didn’t think corals would ever survive long in captivity!
