Under the circumstances, I think you have the right idea to control the Aiptasia rock anemones biologically rather than chemically, Debi. Often the chemical treatments that can eliminate Aiptasia anemones have an unfortunate side effect – they trigger the anemones to release spores before they die, with the result that the Aiptasia eventually reappear with a vengeance in the weeks following the chemical treatments.
A bristle-tail file fish is one option for biological control you can consider, but it’s often not the best option for eradicating Aiptasia anemones in a dedicated seahorse setup, just as you surmised. I would prefer a small colony of decorative shrimp (e.g. Lysmata wurdemanni or Rhynchocinetes species) that will eat Aiptasia rock anemones (if it’s a light infestation) or a group of Berghia nudibranchs to control the Aiptasia if you have a heavy infestation of the anemones.
You can try a file fish of the right type to control Aiptasia rock anemones if you wish, Debi, but proceed with all due caution if you decide to go that route. There are a few things that you must keep in mind, if you do so, Debi.
First of all, not all file fish will browse on me Aiptasia rock anemones, but ALL file fish definitely do like the taste of the frozen Mysis that you will be feeding the seahorses, so there is bound to be some competition for food, but with one small file fish that should not be an insurmountable obstacle by any means. The bristle-tail file fish (Acreichthys tomentosus) that you mentioned in the subject line for this message is the only species I know of that definitely eats Aiptasia glass anemones, Debi, so make sure that you get the right file fish to do the job!
Secondly, although file fish sometimes do well with seahorses, they do often have a tendency to be fin nippers and there is a very definite possibility that your file fish might be one of those individuals that develops a bad habit of going after the dorsal fins of the seahorses. Because of this distinct possibility, if you do try a file fish to help get the Aiptasia rock anemones under control, it would probably be best not to plan on having the file fish be a permanent resident of the tank. By that you mean that I would relocate the file fish to one of your other aquariums (or return it to the pet store where you purchase it for store credit) once it has whittled down the Aiptasia population to manageable proportions. I would then install a small colony (3-5) of peppermint shrimp (Lysmata wurdemanni) or dancing shrimp (Rhynchocinetes durbanensis), both of which are outstanding Aiptasia predators that thrive in small groups and that do very well with seahorses, in order to keep the Aiptasia rock anemones under control from then on…
Thirdly, you’ll need to make certain that the file fish you obtain is 100% healthy before you introduce it to your seahorse tank to make sure that you won’t be exposing the ponies to any pathogens or parasites that the file fish may be carrying. Ideally, you would quarantine the file fish for 30 days to assure that it’s a healthy specimen, so proceed accordingly.
If you bear those precautions in mind, then a bristle-tail pipe fish could possibly be helpful for this problem, but you would be taking a chance…
Personally, I think I would go with the small colony of peppermint shrimp (Lysmata wurdemanni) or dancing shrimp (Rhynchocinetes sp.) right from the start for biological control of the Aiptasia if you are talking about a light to moderate infestation of anemones since you can be confident that, as invertebrates, the shrimp won’t be carrying any pathogens or parasites that might pose a risk to the seahorses.
Or, if you’re confronted with the heavy infestation of the anemones, then I would suggest that you acquire several of the small Berghia nudibranchs to control the Aiptasia instead. The Berghia nudibranchs are obligate predators of Aiptasia anemones, meaning that they are specialized feeders and that the Aiptasia anemones are the only thing that they will eat. If there are only a few Aiptasia anemones in your seahorse tank, that’s not enough to support Berghia nudibranchs which MUST have the Aiptasia available to feed upon or they will starve to death.
On the other hand, if they find abundant Aiptasia anemones, the Berghia nudibranchs will reproduce in the aquarium to deal with the abundance of food.
In your seahorse setup, a small group of peppermint shrimp (Lysmata wurdemanni) or dancing shrimp (Rhynchocinetes sp.) should be able to effectively eliminate a few stray rock anemones with no problems, so that would be my choice for your 20-gallon tank.
Also, Debi, I should mention that you don’t want to include both the predatory shrimp and the Berghia nudibranchs in the same tank, because the peppermint shrimp or dancing shrimp may feed on the nudibranchs as well as the anemones. So pick one or the other, depending on the type of infestation you are dealing with; for the heavy infestation in your seahorse tank, that’s an excellent situation for the Berghia nudibranchs to clean up, whereas for a light infestation of Aiptasia rock anemones, the peppermint shrimp or dancing shrimp are a better choice. (That’s because once the shrimp have taken care of all of the Aiptasia anemones, they will happily make a living by scavenging on leftover Mysis and other organic wastes, whereas the Berghia nudibranchs would simply starve to death.)
Read through the following article carefully, Debi – it will explain all about what make Berghia nudibranchs such effective Aiptasia Anemone predators as well as how to care for them and acclimate them to your aquarium properly:
Okay, Debi, that’s the rundown on the Berghia nudibranchs.
If you haven’t already done so, be sure to check out the following online article as well, Debi, because it has some excellent suggestions for controlling Aiptasia glass anemones that you may find helpful:
Best of luck getting your Aiptasia rock anemones problem under control.
Pete Giwojna, Ocean Rider Tech Support