Okay.. so alot has been brought forth to the community concerning long-term dietary needs for freshwater rays. It has been long thought that a high calorie seafood diet with lots of variety was the best thing to offer, but we are finding that it can have poor side-effects and is not as beneficial as freshwater based foods.
Why is bad you might ask? Well - Seafoods can be very high in proteins and fats, and although large adult rays are more likely to have the ability to digest and benefit from these type of diets, they can also be detrimental. Continious 'bulging' feedings of high fat seafoods can lead to fatty liver disease, which has been a hot topic now for a few months concerning rays.
Many seafoods and shellfish also contain thiaminase. Thiaminase destroys Thiamine (Vitamin B1). Goldfish & Rosie Reds (and most cyprinidae) contain a very high level of thiaminase. Thiamine deficiency can lead to a myriad of problems including neurodegeneration, wasting and death. Tissue Distribution in many living animals is dependent on Thiamine levels. Once Thiaminase is ingested, it has very long lasting effects and does not purge itself from the body. Lack of Thiamine (Vitamin B1) is the primary reason why fish would not be able to properly produce fleshy tissue.
http://www.jbc.org/cgi/reprint/196/1/289
After looking into the dietary pattern of potamotrygon in the wild (http://www.monsterfishkeepers.com/forums/showthread.php?t=175934&highlight=wild+stingray+diet) you can see that they are very much adaptive to whatever their habitat provides them. Depending on seasonality, their diets can change depends on the food sources available. They tend to mainly consume aquatic insects, insect larvae, snails and shrimp. As they grow older, they tend to become a bit more piscivorous and predate on small fish and larger crustacea. I am guessing they also feed on aquatic type worms, similiar to that of the blackworms we often offer them in domestic aquaria. Even vegetation has been found in their diet in the wild.
Side Note: Some species of rays are pretty much insectivorous their whole life - as rays such as Reticulata and Orbignyi tend to have very small jaw/mouth structures that are not designed for crunching or biting, but more-so for grinding and mashing. While other species, like Motoro or Castexi, have very powerful jaw structures that will consume hard shelled crustaceas and eventually small fish when they are larger. Then the other genus, paratrygon, tends to be a complete ambush predator, consuming mainly live fish.
So what about pelletized food? Hikari even put a stingray on the package! Well - Hikari didn't do much research into the dietary needs of rays and if you actually take the time to do a comparison, you will find the hikari massivore pellets are very high in caloric intake and proteins. Likely, these are very hard for a ray to digest and could also lead to other long-term problems if overly fed as a daily staple diet. Obviously, red tail catfish and freshwater stingrays do not eat the same thing - as RTC will predate on other large fish and even mammals, while freshwater rays are more insectivorous than anything.
Heres another good MFK thread on these topics; Overfeeding is bad... mmmk?
http://www.monsterfishkeepers.com/forums/showthread.php?t=134810&highlight=wild+stingray+diet
One thing to also consider is that rays are cold-blooded like reptiles and control their metabolism and digestion by moving in and out of warmer areas. We keep our rays in warm water in captivity, but I think the main reason this has been a recommendation for ray husbandry is the fact that the fatty high protein seafoods we offer might not be digestible without the aid of the higher temperatures. Obviously, small insects and worms will be easier to digest than the prior. However, a ray in the wild that eats a fatty/high protein meal would have the ability to move into the shallow and bask, allowing digestion to be aided.
Perhaps someone was right in recommending rays be kept at 76-78 degrees, rather than the 80-84 most people keep them at. This could have more benefits on the digestion, metabolism, and nutrition intake than the warmer temps. Andersp90 will chime in hopefully, as he has interesting thoughts on this situation..
I have also heard growing a fish too fast can lead to long-term problems. "Power-Growing" is not always beneficial. It seems like our rays grow fairly quickly in captivity, and we have captive adults larger then any wild rays I have seen(BigMama). Perhaps it is more beneficial to grow them slower with a more controlled diet and temperature, then gorging them and turning the temperature way up to get them to eat more and grow more? Perhaps these high temps and high protein diets might show short-term benefits, but they are actually detrimental in the grand scheme of things. I look at high temps/high protein foods more of a conditioning agent/weight gainer/destressing tool rather then a long-term captive husbandry practice.
Like others have noted - Rays need some source of calcium through spines/guts/crustacea, etc.. they also need many other nutritional sources that seafood diets and/or single source diets can not provide. (ie: My rays only eat krill and blackworms - and I am worried they are not getting nearly enough varied nutrition) Mazuri makes a shark/ray vitamin supplement - but the trick is getting a smaller FW ray to eat it. A larger Motoro or Castexi, not a problem as you can probably stuff the pills within the food source. My small retics on the other hand, no chance. So how else would you provide this type of varied nutrition? Lets look..
-------------------------------------
So - What's the other options of food sources?
Earthworms/Red Wigglers - Great varied nutrition as they consume nutrients and minerals from the dirt they live in. Nutrition could be variable based on the quality care of where the worms came from. Also has been some fear of parasites, but highly unlikely with no scientific proof of the theory. I have heard worms are super high in specific vitamins, such as vitamin K, in which other food sources have a very hard time providing.
Blackworms - I have heard these can lead to fatty liver disease also. The rays sure do love them, and they are great for bulking up. They naturally live in freshwater, and carried the same types of varied nutrition that other worms provide. A great food source, but overfeeding could still lead to problems.
Freshwater Fillets - They are suppose to contain less thiaminase, and also be more digestion friendly for freshwater rays. Keep in mind freshwater rays do not consume seafood in the wild so their digestion system is not as capable when it comes to breaking down those types of proteins and fats.
-------------------------------------
So what else is there?
Any ideas for insect-based food cultures?
Maybe we should start looking high and low for a food source that reproduces rapidly but is more nutritionally effecient for the rays?
What is that tiny little water-flea looking bug that sticks to the glass, many people use it as a feeder type ?
What about small live fish, such as gambusia or guppies. They would have the highest level of nutrition as being alive provides the utmost freshness.. and with these, you get the spines/guts nutrition, too!
How come no one in the USA commercial produces live blood worms? I have only seen live bloodworms available in Europe and Asia.
Freshwater crayfish/crabs tend to scare people, because of parasite issues. Nic has a great QT method in place, but its a bit time consuming and not economically effecient. Also, only the larger aggro rays will chomp these crunchy morsels down.
What about a source of freshwater grass shrimp? From what I understand, most of the 'ghost shrimp' is not ghost shrimp at all, but rather Florida Grass Shrimp.. Perhaps someone in the stingray community can find a harvest locale or supplier of these FW grass shrimp. They have benefits such as gut-loading, and this is much like what a ray would eat in the wild. My old LFS owner claims he could get grass shrimp for a penny a peice.. a 1000 shrimp for 10 bucks? Sold. if someone were to start producing these on a major scale and selling them to the stingray community as a source of live food like black worms - it could be a hit!
Maybe someone (Mike) should partner with a fish food company and see about getting a stingray specific food on the market.. A soft-sinking pellet of some sorts, designed for the nutrition needs of rays? I know they have the Mazuri Gel and Mazuri Vits - but that is more Zoo/Aquarium applicable when the home hobbyist would need something more user-friendly. Would be awesome if you could get a company to produce a product for you, but then allow you to label, package, and sell it on your own. -I will take 2 bottles of H20CustomAquatic Ray Pellets please
-
So what else is there? Some sort of freshwater insect? Who has ideas?
I have a feeling their might be an 'untapped' resource of a very good stingray food out there - we just need to find it.. but where?
Discuss
Why is bad you might ask? Well - Seafoods can be very high in proteins and fats, and although large adult rays are more likely to have the ability to digest and benefit from these type of diets, they can also be detrimental. Continious 'bulging' feedings of high fat seafoods can lead to fatty liver disease, which has been a hot topic now for a few months concerning rays.
Many seafoods and shellfish also contain thiaminase. Thiaminase destroys Thiamine (Vitamin B1). Goldfish & Rosie Reds (and most cyprinidae) contain a very high level of thiaminase. Thiamine deficiency can lead to a myriad of problems including neurodegeneration, wasting and death. Tissue Distribution in many living animals is dependent on Thiamine levels. Once Thiaminase is ingested, it has very long lasting effects and does not purge itself from the body. Lack of Thiamine (Vitamin B1) is the primary reason why fish would not be able to properly produce fleshy tissue.
http://www.jbc.org/cgi/reprint/196/1/289
After looking into the dietary pattern of potamotrygon in the wild (http://www.monsterfishkeepers.com/forums/showthread.php?t=175934&highlight=wild+stingray+diet) you can see that they are very much adaptive to whatever their habitat provides them. Depending on seasonality, their diets can change depends on the food sources available. They tend to mainly consume aquatic insects, insect larvae, snails and shrimp. As they grow older, they tend to become a bit more piscivorous and predate on small fish and larger crustacea. I am guessing they also feed on aquatic type worms, similiar to that of the blackworms we often offer them in domestic aquaria. Even vegetation has been found in their diet in the wild.
Side Note: Some species of rays are pretty much insectivorous their whole life - as rays such as Reticulata and Orbignyi tend to have very small jaw/mouth structures that are not designed for crunching or biting, but more-so for grinding and mashing. While other species, like Motoro or Castexi, have very powerful jaw structures that will consume hard shelled crustaceas and eventually small fish when they are larger. Then the other genus, paratrygon, tends to be a complete ambush predator, consuming mainly live fish.
So what about pelletized food? Hikari even put a stingray on the package! Well - Hikari didn't do much research into the dietary needs of rays and if you actually take the time to do a comparison, you will find the hikari massivore pellets are very high in caloric intake and proteins. Likely, these are very hard for a ray to digest and could also lead to other long-term problems if overly fed as a daily staple diet. Obviously, red tail catfish and freshwater stingrays do not eat the same thing - as RTC will predate on other large fish and even mammals, while freshwater rays are more insectivorous than anything.
Heres another good MFK thread on these topics; Overfeeding is bad... mmmk?
http://www.monsterfishkeepers.com/forums/showthread.php?t=134810&highlight=wild+stingray+diet
One thing to also consider is that rays are cold-blooded like reptiles and control their metabolism and digestion by moving in and out of warmer areas. We keep our rays in warm water in captivity, but I think the main reason this has been a recommendation for ray husbandry is the fact that the fatty high protein seafoods we offer might not be digestible without the aid of the higher temperatures. Obviously, small insects and worms will be easier to digest than the prior. However, a ray in the wild that eats a fatty/high protein meal would have the ability to move into the shallow and bask, allowing digestion to be aided.
Perhaps someone was right in recommending rays be kept at 76-78 degrees, rather than the 80-84 most people keep them at. This could have more benefits on the digestion, metabolism, and nutrition intake than the warmer temps. Andersp90 will chime in hopefully, as he has interesting thoughts on this situation..
I have also heard growing a fish too fast can lead to long-term problems. "Power-Growing" is not always beneficial. It seems like our rays grow fairly quickly in captivity, and we have captive adults larger then any wild rays I have seen(BigMama). Perhaps it is more beneficial to grow them slower with a more controlled diet and temperature, then gorging them and turning the temperature way up to get them to eat more and grow more? Perhaps these high temps and high protein diets might show short-term benefits, but they are actually detrimental in the grand scheme of things. I look at high temps/high protein foods more of a conditioning agent/weight gainer/destressing tool rather then a long-term captive husbandry practice.
Like others have noted - Rays need some source of calcium through spines/guts/crustacea, etc.. they also need many other nutritional sources that seafood diets and/or single source diets can not provide. (ie: My rays only eat krill and blackworms - and I am worried they are not getting nearly enough varied nutrition) Mazuri makes a shark/ray vitamin supplement - but the trick is getting a smaller FW ray to eat it. A larger Motoro or Castexi, not a problem as you can probably stuff the pills within the food source. My small retics on the other hand, no chance. So how else would you provide this type of varied nutrition? Lets look..
-------------------------------------
So - What's the other options of food sources?
Earthworms/Red Wigglers - Great varied nutrition as they consume nutrients and minerals from the dirt they live in. Nutrition could be variable based on the quality care of where the worms came from. Also has been some fear of parasites, but highly unlikely with no scientific proof of the theory. I have heard worms are super high in specific vitamins, such as vitamin K, in which other food sources have a very hard time providing.
Blackworms - I have heard these can lead to fatty liver disease also. The rays sure do love them, and they are great for bulking up. They naturally live in freshwater, and carried the same types of varied nutrition that other worms provide. A great food source, but overfeeding could still lead to problems.
Freshwater Fillets - They are suppose to contain less thiaminase, and also be more digestion friendly for freshwater rays. Keep in mind freshwater rays do not consume seafood in the wild so their digestion system is not as capable when it comes to breaking down those types of proteins and fats.
-------------------------------------
So what else is there?
Any ideas for insect-based food cultures?
Maybe we should start looking high and low for a food source that reproduces rapidly but is more nutritionally effecient for the rays?
What is that tiny little water-flea looking bug that sticks to the glass, many people use it as a feeder type ?
What about small live fish, such as gambusia or guppies. They would have the highest level of nutrition as being alive provides the utmost freshness.. and with these, you get the spines/guts nutrition, too!
How come no one in the USA commercial produces live blood worms? I have only seen live bloodworms available in Europe and Asia.
Freshwater crayfish/crabs tend to scare people, because of parasite issues. Nic has a great QT method in place, but its a bit time consuming and not economically effecient. Also, only the larger aggro rays will chomp these crunchy morsels down.
What about a source of freshwater grass shrimp? From what I understand, most of the 'ghost shrimp' is not ghost shrimp at all, but rather Florida Grass Shrimp.. Perhaps someone in the stingray community can find a harvest locale or supplier of these FW grass shrimp. They have benefits such as gut-loading, and this is much like what a ray would eat in the wild. My old LFS owner claims he could get grass shrimp for a penny a peice.. a 1000 shrimp for 10 bucks? Sold. if someone were to start producing these on a major scale and selling them to the stingray community as a source of live food like black worms - it could be a hit!
Maybe someone (Mike) should partner with a fish food company and see about getting a stingray specific food on the market.. A soft-sinking pellet of some sorts, designed for the nutrition needs of rays? I know they have the Mazuri Gel and Mazuri Vits - but that is more Zoo/Aquarium applicable when the home hobbyist would need something more user-friendly. Would be awesome if you could get a company to produce a product for you, but then allow you to label, package, and sell it on your own. -I will take 2 bottles of H20CustomAquatic Ray Pellets please
-So what else is there? Some sort of freshwater insect? Who has ideas?
I have a feeling their might be an 'untapped' resource of a very good stingray food out there - we just need to find it.. but where?
Discuss
