Goldfish are Nutritious

[aclockworkorange]

I was also curious if this guy was a troll so I did some digging and found this post from him:

Oddball, would you be interested in an in-depth conversation about feeder goldfish? I may be able to dredge up some useful information. I am a producer, and I have some contacts. I have read your posts and they are thoughtful, but I think the conversation would benefit from more specific data.

So I think that answers the question as to why the OP is posting this...

 

[probassfisher010]

Hey SJkoi, Im not Bob Fenner..I just copied an article he wrote on the subject. Here is Bob Fenners credentials:
Robert (Bob) Fenner is a content provider to the pet-fish (ornamental) aquatics hobby and trade, dive/travel adventure and underwater natural history genres; writing, photography and videography. Though retired since 1994, he continues to produce in this field as well as consult on aquaculture and public aquarium installations.
Bob has "lived" the science, hobby and business of aquatics in the Philippines, Japan and United States. All phases; collector, wholesale, jobber, retail, design, construction and maintenance. All levels; manager, owner, hatchery worker, retail clerk, technician. Except for a stint teaching high school sciences for four years, he has worked all his life in the field of ornamental aquatics.
Academic experience includes fifteen years of college, a couple of life science degrees and a teaching credential for chemistry, physics and biology. Published works include several studies on aquatic biological and chemical questions, and an extensive book and article publishing (helped author a few books, The Conscientious Marine Aquarist, Fishwatcher's Guide to the Tropical Marine Aquarium Fishes of the World, Natural Marine Aquariums Reef Invertebrates...) and photographic background in aquatic industry and hobby fields. Have taught High School sciences and Marine Sciences and Aquariology courses at the State University, University of California levels.
Bob has been an avid aquatic hobbyist since day one and is active in hobbyist and scientific organizations. He has served on numerous Boards, judged shows and given many programs.
Helped form and run (President) of the employee-owned corporation, Nature Etc., Inc. in San Diego, started in 1973; a turn-key operation in the field of ornamental aquatics, designing and building ponds, lakes, fountains and waterfalls (Aquatic Environments), designing, installing custom aquarium systems and maintenance (Aquatic Life Services), and operating retail outlets (Wet Pets).... currently does consulting, content provision to the trade, sciences and hobby of aquaristics.

 

[sjkoi]

I was also curious if this guy was a troll so I did some digging and found this post from him:




So I think that answers the question as to why the OP is posting this...

I have been in aquaculture since 1986 as a fishery biologist. I have worked with trout, sturgeon, bass, fancy goldfish, feeder goldfish, koi, catfish, sturgeon and other species. Currently I am the owner of a small koi farm in California. The koi is a labor of love, but has been put on hold as I attempt to straighten out another piece of property we recently took over that raised feeder goldfish. I am not married to the idea of raising feeder goldfish, and or any other species and so have been thinking about what direction I should take our venture. I have kept oscars for awhile and have one at the house which I feed with gambusia from the backyard koi pond. I have been doing my research. I need to know if live foods are a product that I can feel good about producing from an ethical basis and long term basis. If not then I'll turn the operation in a different direction. I want to support the hobby.

I can appreciate the skepticism. It’s warranted. But, I promise you that I am only playing devil’s advocate to the notion that live foods should be avoided at all costs. My real belief is that live foods have a place in the diet of a true piscivore but there are drawbacks and concerns that should be clearly understood. Not a radical position. I am hoping that through this discussion the tradeoffs and benefits of using live diets vs. commercially prepared diets is better understood and how to manage both to provide our fish with a diverse and nutritionally complete diet is improved. I have taken the pro-side of the argument because no one else has. I can see it both ways. If the moderators have concerns with my posts, and if I cross the line of civil discussion to self-promotion, I will understand. For that reason I don’t want to get into the specifics of where I am located and or accept any personal emails that in anyway solicit business. I don’t have anything to sell. Period.

My posts come slowly. The farm and family commitments make this a slow process for me. I am learning and coming at this from a totally different perspective. I have reared fish my entire adult life and one of the truths I have seen repeated over and over again is the value of a natural diet. This is especially true in the early life stages. The single most important factor in fry survival is the presence of natural prey items starting with rotifers and moving on up the food chain. I have yet to find a commercially prepared diet at any price that can hold a candle to live foods and give me the vitality and survivability that I see in natural diets. Fry that have had a rich source of natural feed grow more quickly, are stronger and vital. They train onto artificial diets more quickly and are more robust when handled. Fry that do not receive a natural diet are weak, slow growing and prone to disease. The best commercial diets for piscivores are up to 60% fish meal. What does that tell you. The development of modern diets have been attempts to provide sufficient nutrition that is stable, cost effective and convenient for the farmer. To manage all three there have been a lot of compromises. Most of these compromises are fine for lower trophic species like tilapia and catfish, but true piscivores are not well adapted to eat most of what you can buy off the shelf.

Rich

 

[sjkoi]

Thanks Jesse. I should have figured that out. If I can manage it I'll try to summarize what I learned about lake trout later tonight and the role of thiaminase in the low viability of its spawn.

 

[probassfisher010]

Just a question, what fish have you had that is a true piscivore. I have read that you feed your Astronotus ocellatus feeder fish, and as I presume, this is the vast majority of its diet? If this Oscar is the "piscivore" that you keep mentioning, then there is your first invalid assumption. Oscars in the wild do not eat solely fish, and especially not coldwater fish such as goldfish and Rosy Reds. Oscars in the wild actually are omnivores eating mostly insects, fruit, and of course fish. However, the fish that they are known to usually eat are small catfish. So unless you have a true piscivore, that solely eats 100% fish in the wild, then your argument is already invalid.

 

[sjkoi]

Jesse, I would not use my own limited experience as a hobbyist for a basis to make any points on this forum. When I refer to a true piscivore I was making a general reference to any species that has a short gut and is adapted to eat high protein diets. The term "true piscivore" was inaccurate as no fish species consumes strictly a diet of other fish throughout its entire life. I stand corrected.

 

[RD.]

Rich,

No one here has stated that live food should be avoided at all costs. If you checked out the link to the gar discussion it should be quite clear that not even I would suggest attempting to feed a juvenile gar pellets, as most will simply refuse to feed.

Having said that, you are viewing this from commercial eyes, as a farmer, something that very few people here are going to be able to relate to.

The development of modern diets have been attempts to provide sufficient nutrition that is stable, cost effective and convenient for the farmer. To manage all three there have been a lot of compromises. Most of these compromises are fine for lower trophic species like tilapia and catfish, but true piscivores are not well adapted to eat most of what you can buy off the shelf.

Piscivores are not well adapted at assimilating much of what one might expect to find in a commercial farm feed (such as large amounts of terrestrial based plant matter; corn-wheat-soybean, etc) but most hobbyists don't have to rely on commercial farm feed to raise their fish. There are commercial diets available to hobbyists that are low in carbohydrate content, and high in amino acid content, from various high quality & relatively expensive sources, such a Herring meal, South Antarctic Krill meal, Squid meal. etc. A smorgasbord of essential amino acids, with overall nutrient profiles that make a goldfish look pale in comparison.

The only compromise that I see being made is that by the farmer, who due to their commercial application must seek lower cost alternative feeds.

There are millions of piscivores raised on pellet feed by hobbyists & commercial breeders world-wide each year, that are neither weak, slow growing or prone to disease. Yes, some species will do better when started out on live feed, but that seems like a far cry from you are stating.

 

[boldtogether]

I like goldfish, they're pretty. They're just trying to make it in this world, cant we make it better for them? Goldfish may be a good source of protein blah, blah, blah....so are soybeans. Point is, we have MODERN alternatives. Better, high quality alternatives and our pets benefit from this. Should you only feed a dog raw meat? Would it hunt at In-n-Out if it were wild? Do we really want "wild"?
Just because you could doesnt mean you should and as far as a "treat" goes, get him a double-double...animal style.

 

[sjkoi]

A simple crude protein or crude fat percentage doesn't prove anything. One would need to compare amino acid profiles, fatty acid profiles, total vitamin & trace mineral content, total digestibility, feed conversion ratios, color enhancing properties of the feed, a comparison of potential bioactive compounds contained in the food source, which in aquaculture have been shown to have biological effects in fish such as growth promotion, immunostimulation, anti-stress, anti-bacterial, anti-fungal, anti-virals. etc-etc-etc

This is more than crude fat and crude protein percentages, mineral and trace mineral dietary numbers. You are given that this is fish tissue which gives you an excellent idea of the amino acid profile and its digestibility. Crude percentages of protein and fat on a feed label aren't very meaningful unless you know what the contents are. Even then you don't know the quality of the product. Fishmeal comes in different grades and freshness. We are talking whole, live fish and that is a lot of information in that statement. As for fat content, its fresh unprocessed fish oil. These are the gold standards in fish diets. We are not talking beef tallow, meat and bone meal, feather meal or dried blood. Its whole fish.

Goldfish - Crude protein 58.8%, fat 8.5%, energy 4.15 Kcal/g, Ca 6.99%, P 4.36%, Mg 0.17%, Na 0.65%, K 1.22%, Cu 14 ppm, Fe 307 ppm, Zn 225 ppm, Mn 64 ppm, Se 1.22 ppm

Minnows - Crude protein 64.6%, fat 14.1%, energy 4.97 Kcal/g, Ca 3.71%, P 3.01%, Mg 0.19%, Na 0.59%, K 1.38%, Cu 13 ppm, Fe 225 ppm, Zn 165 ppm, Mn 17 ppm Se 0.82 ppm

One can pump a fish up at lightning speeds using a cheap generic trout chow with a high protein high lipid content, but that type of growth comes with a hidden price tag, that being excessive lipid deposition in the liver, and premature death of the fish.

Yes, fish in general have a low tolerance for high carbohydrate diets. Piscovers are especially prone to diseases associated with high carbohydrate diets. There was a study in the Journal of The World Aquaculture Society (Vol. 33, No.4) where largemouth bass suffered serious liver damage and high mortality rates as a consequence of being fed a trout diet with excessive carbohydrate levels (>27%). I don’t know if you intended to make my case here for me or not.

I would also like to point out that fat levels in feeder goldfish could vary vastly from one batch to the next, depending on various factors such as species, size/age, body condition, etc.

I disagree with you on this point. The bulk of feeders sold are merely fry. The balance of their free metabolic energy goes to tissue development. Not until fish exceed 100 grams will they begin to sexually mature and begin laying on fat stores. So while there will be some variation at the smaller sizes (aprox. 1 gram), I don't believe the numbers would range widely.

With regards to thiaminase ......

That's probably due to the fact that there aren't any warm water species of fish that only consume prey that contain large quantities of thiaminase. Their other various prey would likely contain enough B1 to negate any effect from those food stuffs that contain thiaminase.

Possibly, no one really knows why, but there is a good theory as to why there are no recorded cases of thiamin(B1) deficiency in wild warm-water species. We know that frozen fish that contain thiaminase will within a short period of time loose their thiamin. This was first seen in mink and has been well documented and is an important consideration when working with any species that contains thiaminase. Thiaminase is believed to be contained within individual cells encapsulated to prevent the degradation of thiamin. What it's function is within the cell is a mystery. Its source is also a mystery. Freezing ruptures the cell and releases thiaminase which in time will deactivate thiamin, even while frozen under the best of conditions. In live fish that contain thiaminase these cell structures are still intact at the time the prey is captured. Not all tissue will contain equal amounts of thiaminase. The gills and spleen have high concentrations while the muscles have little or none. Muscle tissue is a rich source of thiamin. The critical amount of thiamin in fish for normal function is extremely low (measured in nano moles). It is believed that as the tissue moves through the gut free thiamin is simultaneously being absorbed by the fish and degraded by thiaminase. Not all tissue will digest at the same rate. Since thiaminase can not cross over into the bloodstream, any thiamin absorbed is captured by the fish which is why it is believed that warm-water species that feed on live thiaminase containing species do not suffer thiamin deficiency. Any other feed items within the gut at the time a thiaminase containing item is present will also be acted upon by the same enzyme. Finally, thiaminase only hangs out in the gut for as long as it takes to digest the prey item.

Many species of fish & invertebrates contain thiaminase and when ingested in large quantities it destroys the natural thiamin (vitamin B1) which in turn can cause vitamin deficiency. In fish, vitamin B1 deficiencies can lead to stunting, illness, and premature death. Goldfish feeders are known to be high in thiaminase, as are shrimp/prawns, both of which are commonly used to feed large predatory species in captivity.

Yes, it appears that thiaminase is wide spread among the lower trophic species. It would be a fair assumption that most species of fish contain some thiaminase either in their tissue or their gut. We know that some plants, fungi, and bacteria produce thiaminase. We also know that it is widespread amongst the clupeidae and cyprinidae which are two of the largest families of fish. If you factor in other species known to contain thiaminase and those species that eat fish or other items that contain thiaminase, you have a pretty large group. If you are using a species of fish that has not been shown to contain thiaminase, I would still recommend you allow several days for the fish to purge its gut if you intend to freeze it for feeding later. Or, cook it at a temperature of at least 100 C to neutralize the thiaminase prior to storing.

the Great Lakes region, vitamin B1 deficiencies have also been the cause of a great deal of studies, and have been linked to both trout & salmon ingestion of alewifes & smelt, both known to be high in thiaminase.
http://www.glsc.usgs.gov/main.php?c...itiatives0&menu=research_initiatives_thiamine

Yep, good study. After several years of feeding thiaminase containing alewives to lake trout it was shown that egg viability decreased. The alewives are a non-native species that have invaded the Great Lakes and it seems clear that the thiaminase contained in alewives is the cause for low survival of lake trout eggs. Thiamin levels in the lake trout studied varied throughout the year but in the winter levels troughed. One of the authors of the study speculated to me that it may have been a factor of the lake trout needing to binge feed in the warmer months to sock away enough nutrients to carry it through the winter. As the winter progresses lake trout may deplete their stores of thiamin. Another theory is that the colder water temperature in winter slows down the metabolism of lake trout to the point where it can not absorb enough thiamin through the alewives it captures before thiaminase deactivates the available B1. This would make sense in the same way that Thiaminase remains active even during freezing. It also supports the theory that under warmer conditions thiamin uptake is sufficient to meet metabolic needs. It was emphasized to me that a lot is not know about thiaminase and how it acts, but that unless I intended to breed cold-water species of fish like brook trout, I shouldn't be concerned if I was using a live feed.

There is no warm-water analogy to this event that anyone has been able to find. Why, no one knows, but again, not much is known about thiaminase.

With regards to both tropical & marine fish, the article below by Dr. Marco Lichtenberger is perhaps one of the best reads on this subject.
http://www.wetwebmedia.com/ca/volume_6/volume_6_1/thiaminase.htm


Cheers!

I have read the article several times. It was the reason that I thought I should look into thiaminase further. I will tell you that I had a completely different understanding of the article after I looked into it than before. But, this enough for now, I’ll save that for another night. Thanks for your insight.

Rich

 

[TaratronVaeVictus]

So out of curiosity, do you own stock in feeder farms or something, because I can't imagine why else you keep pushing that mass produced and poorly bred feeder fish are perfect for other fish to eat.

I have snakes and largely because of the cost of feeding picky picky ball pythons, I raise my own mice. I control the diet, who breeds, who is fed, and because of this control I can eliminate weak mice or ones who don't fit the bill of a colonial animal. You start with better, you end with better. And I don't count mass bred and produced feeder mice as better than, essentially, homegrown.