Re: Gymnothorax tile tumors. Malnutrition? - 10/07/2007
The eel's tumors are gone! I appreciate your advice very much. There has been a lot of success with keeping him healthy, along with some noticeable growth in size. His food has been injected with the appropriate supplements as well. The need for a new tank is growing, and I believe I could probably get him a new one in the next few months. Adding another question, I found this little packet in the LFS called "Phosphate-X" or "Phos-X." Something like that name. The description on the label says it absorbs phosphate, nitrates, and nitrites. I don't rely on this little packet about the size of a sticky-note and still perform water changes, I was only wondering if it helped. On a different matter, the eel eats about twice a week based on the information I found on your website. I used to offer krill that was accepted from time to time but read that it wasn't good for the eel and promptly stopped feeding that. Silversides have been a new favorite alongside shrimp, and squid are accepted when the eel feels like eating them. (the food is removed after a few hours as you suggested as not to pollute the water) I'd like him to live as long as possible, so I've done everything I can, and will continue to do so. The brackish water isn't rotting the wood so far, and the salinity is as you suggested. While on that, is there anything better than a regular hydrometer? Perhaps something electronic?
<A hydrometer is fine for brackish water fish. Any inaccuracy will be well within the tolerances of the fish. In fact, most brackish water fish like a bit of variation from time to time. But your filter isn't quite so accommodating, so it's best not to vary the SG more than a couple of points on the SG scale at any one time (i.e., SG 1.010 to 1.012 is fine, but 1.010 to 1.018 not so much).>
Another question. My Gymnothorax tile lives in high-end brackish but what is their environment like out where they live if they're from Asia?
<The problem here is that they are almost certainly migratory, like most large brackish water fish. So there's no "perfect" habitat. These morays are found -- as adults -- in completely freshwater as well as in the sea, and they seem to move about between the upper and lower estuary. They're neither completely saltwater fish nor true freshwater fish, but something in between. That said, like a lot of eels, their main habitat is murky, muddy water where their ability to burrow, negotiate rubble and locate food under poor visibility conditions is useful. A typical environment would probably be sticky mud at the bottom, murky water, large rocks and waterlogged tree trunks, and rocky reefs. Hardly attractive for an aquarium!>
Will any aquatic plants survive in the brackish water, and what kind of decoration should be used to make it look like Gymnothorax tile habitat?
<There are brackish water plants, such as Cryptocoryne ciliata and Crinum calamistratum in the trade, as well as the very hardy Java fern that does well in brackish water, but there's little point to using them. They aren't authentic for the sorts of habitats these eels will be living in. Eels favour dark, murky places and they don't like bright light. Much better to create something with a tall, rocky reef-like structure so the eel can hide and wind itself around. These eels don't so much swim as slither through things, and the more 3D the aquarium, the better. Big mounds of holey rocks would probably work very nicely. Something like a reef tank arrangement. What you want to avoid is anything too rough and definitely nothing unstable, as these fish are quite powerful and excellent diggers. I'd personally be looking at an oyster reef habitat. These are really important environments in brackish water habitats and easy to replicate. Simply gather lots of oyster shells (easy enough to buy as food, if nothing else) and use silicone to cement them to some sort of rock, such as tufa rock.>
I'm thinking that if I make it as naturalistic as possible he'll live longer than what is usually achieved in captivity.
<A good approach. The reason these eels don't survive is not really a mystery. A few things seem consistent. Keeping them in too-low a salinity doesn't help, and usually leads to hunger strikes. So at least SG 1.005 is required, and probably SG 1.010 for best results. On the other hand, there's no evidence they "swim out to sea" when mature, so keeping them in saltwater tanks likely isn't required provided the salinity is at least at or above SG 1.010. Diet is another factor. With these eels, and indeed any other predatory fish, I'm a fan of the "little but often" approach. Yes, you can feed them a big prawn one day and skip the next. But the risk with predatory fish is they regurgitate the food and pollute the tank. I'd sooner give small morsels each night, so that there's no risk of major pollution. At SG 1.010 upwards you can use a protein skimmer with success. While not crucial, these devices to help manage the nitrate by removing organic waste from meaty foods before they decay. So in the long run, a skimmer can end up saving you money by reducing the frequency of water changes. Of course, you still need to aim for the same relatively low nitrate level (I'd suggest <50 mg/l) but generally morays are fairly tolerant of this. Hope this helps, Neale>

Re: Gymnothorax tile tumors. Malnutrition? - 10/07/2007
The eel's tumors are gone! I appreciate your advice very much. There has been a lot of success with keeping him healthy, along with some noticeable growth in size. His food has been injected with the appropriate supplements as well. The need for a new tank is growing, and I believe I could probably get him a new one in the next few months. Adding another question, I found this little packet in the LFS called "Phosphate-X" or "Phos-X." Something like that name. The description on the label says it absorbs phosphate, nitrates, and nitrites. I don't rely on this little packet about the size of a sticky-note and still perform water changes, I was only wondering if it helped. On a different matter, the eel eats about twice a week based on the information I found on your website. I used to offer krill that was accepted from time to time but read that it wasn't good for the eel and promptly stopped feeding that. Silversides have been a new favorite alongside shrimp, and squid are accepted when the eel feels like eating them. (the food is removed after a few hours as you suggested as not to pollute the water) I'd like him to live as long as possible, so I've done everything I can, and will continue to do so. The brackish water isn't rotting the wood so far, and the salinity is as you suggested. While on that, is there anything better than a regular hydrometer? Perhaps something electronic?
<A hydrometer is fine for brackish water fish. Any inaccuracy will be well within the tolerances of the fish. In fact, most brackish water fish like a bit of variation from time to time. But your filter isn't quite so accommodating, so it's best not to vary the SG more than a couple of points on the SG scale at any one time (i.e., SG 1.010 to 1.012 is fine, but 1.010 to 1.018 not so much).>
Another question. My Gymnothorax tile lives in high-end brackish but what is their environment like out where they live if they're from Asia?
<The problem here is that they are almost certainly migratory, like most large brackish water fish. So there's no "perfect" habitat. These morays are found -- as adults -- in completely freshwater as well as in the sea, and they seem to move about between the upper and lower estuary. They're neither completely saltwater fish nor true freshwater fish, but something in between. That said, like a lot of eels, their main habitat is murky, muddy water where their ability to burrow, negotiate rubble and locate food under poor visibility conditions is useful. A typical environment would probably be sticky mud at the bottom, murky water, large rocks and waterlogged tree trunks, and rocky reefs. Hardly attractive for an aquarium!>
Will any aquatic plants survive in the brackish water, and what kind of decoration should be used to make it look like Gymnothorax tile habitat?
<There are brackish water plants, such as Cryptocoryne ciliata and Crinum calamistratum in the trade, as well as the very hardy Java fern that does well in brackish water, but there's little point to using them. They aren't authentic for the sorts of habitats these eels will be living in. Eels favour dark, murky places and they don't like bright light. Much better to create something with a tall, rocky reef-like structure so the eel can hide and wind itself around. These eels don't so much swim as slither through things, and the more 3D the aquarium, the better. Big mounds of holey rocks would probably work very nicely. Something like a reef tank arrangement. What you want to avoid is anything too rough and definitely nothing unstable, as these fish are quite powerful and excellent diggers. I'd personally be looking at an oyster reef habitat. These are really important environments in brackish water habitats and easy to replicate. Simply gather lots of oyster shells (easy enough to buy as food, if nothing else) and use silicone to cement them to some sort of rock, such as tufa rock.>
I'm thinking that if I make it as naturalistic as possible he'll live longer than what is usually achieved in captivity.
<A good approach. The reason these eels don't survive is not really a mystery. A few things seem consistent. Keeping them in too-low a salinity doesn't help, and usually leads to hunger strikes. So at least SG 1.005 is required, and probably SG 1.010 for best results. On the other hand, there's no evidence they "swim out to sea" when mature, so keeping them in saltwater tanks likely isn't required provided the salinity is at least at or above SG 1.010. Diet is another factor. With these eels, and indeed any other predatory fish, I'm a fan of the "little but often" approach. Yes, you can feed them a big prawn one day and skip the next. But the risk with predatory fish is they regurgitate the food and pollute the tank. I'd sooner give small morsels each night, so that there's no risk of major pollution. At SG 1.010 upwards you can use a protein skimmer with success. While not crucial, these devices to help manage the nitrate by removing organic waste from meaty foods before they decay. So in the long run, a skimmer can end up saving you money by reducing the frequency of water changes. Of course, you still need to aim for the same relatively low nitrate level (I'd suggest <50 mg/l) but generally morays are fairly tolerant of this. Hope this helps, Neale>