Live Fish As Food - Nutritional Value & Concerns

[TTTT]

Although I don't feed my fish feeders regularly, I do drop a rosy minnow in every once in a while. You have to admit it's awesome to watch a fish chase another fish

 

[squilla]

I have a 15" male zebra mantis shrimp (Lysiosquillina maculata) and a 13" Atlantic green moray eel. Both are fed fresh, pre-quanatined/ freshwater dipped large damselfishes twice a week. It's an investment, but I think it's better to have fewer predatory animals in a collection so you can spend more on obtaining proper foods instead of purchasing too many predators, and only having enough money left over to feed them sub-par food items.

 

[Octofasciata Aficionado]

I keep a ready supply of guppies, but they are by no means a staple. In fact I'll go weeks with out giving one to my Jack, I usually use them as anti-depressants whenever he gets mopy. Nothing else perks him up quicker, and it's good exercise to boot.

 

[RD.]

Ballast substances
These are effective against intestinal inertia. This frequently occurs, e.g., if discus are fed food low in ballast substances, such as scraped beef heart, for a longer time. Beisdes lacking ballast substances, that kind of nutrition is much too single-sided and does not meet the natural requirements.

Carbohydrates
Benefits: Carbohydrates are utilized by being chemically converted to sugars and then absorbed as an energy source, or being stored in the tissues for later use. Carbohydrates are important because they are essential for the conversion of amino acids and fats into various other components required for normal functioning.
Negative effects: Excessive amounts of carbohydrates in the fish's diet can cause liver degeneration and associated diet-related diseases.

Fats
Benefits: These allow fish to synthesize it with other fatty acids.
Negative effects: Do not use foods containing too much fats. Too much fats will simply accumulate and can cause organ failure in the fish's body system-a case similar to humans. Carnivorous fish will require no more than 6% crude fat content on their diet.

Fiber
Benefits: Herbivorous fish will really benefit from this as fiber is often found in plants they eat.
Negative effects: Fish cannot digest all fiber which is why no more than 10% fiber content is recommended for herbivores and no more than 4% for carnivores and omnivores.

Proteins:
Benefits: growth and development. Young fish will need more proteins compared to the adults. Herbivorous fish have a lower protein requirement compared to carnivores and omnivores.
Deficiency: stunting of fish's growth.
Negative effects: Too much proteins can cause bloat. Herbivorous fish should never be fed with food containing too much proteins as they do not require too much proteins. No more than 30% crude protein content shall be provided to herbivores whereas carnivores will really require at least 45% or more. This will be explained further below.

Minerals
Minerals are important for the fish to maintain a healthy body system. Flake foods often have very adequate mineral content and have a much longer shelf life compared to vitamins.
Below are the following minerals with information provided.

Calcium
Benefits: Fish need calcium like we do. This is important for strong bone structure thus preventing bone defects.
Deficiency: Deformed bones are often a result from lack of calcium.

Copper
Deficiency: Reduced growth, cataracts

Iodine
Benefits: Iodine is also very important preventing goiter in fish.
Deficiency: This is a very common mineral deficiency in fish. A fish lacking in iodine can suffer goiter, an inflammation in the thyroid glands.
Treatment: Iodine can be found iodized table salt. The use of table salt, however, is widely debated although most fishkeepers have used it with absolutely no problems.

Iron
Deficiency: Reduced growth and poor food conversion, anemia
Negative effects: Too much iron can damage or even kill the fish.

Magnesium
Deficiency: Reduced growth, cataracts, bone deformation, degeneration of muscles, behavioural changes

Manganese
Deficiency: Reduced growth, dwarfism, abnormal tail growth, cataracts

Phosphorus
Benefits: Prevention and recovery of fish from Head and Lateral Line Erosion (HLLE)
Deficiency: Lack of phosphorus can cause HLLE
Treatment: Foods available for the fish should contain large quantities of calcium, phosphorus and other trace elements. Fish often rely on foods rather than the water for proper growth and development. Plants are said to contain phosphorus so they can be beneficial in almost every tank.

Selenium
Deficiency: Reduced growth, cataracts, muscular dystrophy

Zinc
Deficiency: Reduced growth, high mortality, dwarfism, fin/skin erosion

While I'm a bit late to the party, there are a few major flaws in the info above that I felt needed to be addressed.

1. Fat - while lipids do serve as transporters for fat soluble vitamins, their main purpose in most commercial diets is to provide an energy source. Carnivores (as well as juveniles that have higher metabolic rates) are most certainly able to consume more than 6% crude fat, it's all relative to the size & growth stage of the fish, as well as each fishes energy levels. While excessive fat can indeed cause health issues, at the same time if not enough fat is provided in the diet, amino acids (protein) end up being utilized as an energy source, instead of being utilized for growth, tissue repair, etc. A max 6% crude fat content is definitely a reasonable number for most applications, but certainly not for all carnivores, and definitely not for all stages of growth.


2. Protein - perhaps the most misunderstood subject when it comes to fish nutrition. For a starter, too much protein does not cause bloat. It doesn't matter how many times someone repeats this on an online chat forum, it doesn't make it become a fact. Bloat is seldom triggered by diet alone, and if/when it is, it's typically triggered by overfeeding, and/or excessive grain/carb content in the feed. Poor digestibility of a feed may trigger bloat like symptoms, but protein won't be the cause, unless that protein is derived from low grade ingredients, with very low overall digestibility. Excess protein is typically excreted as waste, and while excessive amounts of protein may tax the organs, and even have a negative effect on growth due to the energy required for the organs to break those excess amino acids down, and excrete them, protein in and of itself will not, and does not, cause bloat.

With regards to protein requirements, yet another MAJOR misconception in this hobby, that being carnivores require a set value of crude protein in order to thrive in captivity, and if one meets that set value those requirements will have been met.

There are many ways that one can boost the nitrogen (crude protein) level in a commercial food, but that doesn't necessarily mean that all of that protein is in a form that a fish can fully assimilate. I could formulate a feed with a 65% crude protein content, & call it "Gigantic Monster Fish" food, using nothing but soybean, yet most carnivores would only be able to assimilate a small fraction of that protein. When one is comparing crude protein content in a food, THE most important part of the protein equation is what that protein was derived from, not just what the percentage is. A common mistake made by many hobbyists.






With regards to feeding live ......


The largest freshwater carnivores in North America, Acipenser transmontanus (White Sturgeon), are raised commercially (such as the fish below) exclusively on pellet food that typically consists of 40-45% crude protein, and exceed both size & weight of the vast majority of tropical fish kept in captivity.

I agree that aquaculture facilities dont feed live because it's not economical or overly practical, and that it's possible to get better gains on live food. Having said that IMO a LOT of people in this hobby become too fixated on just growing BIGGER, and FASTER, and seldom consider longevity. There are certainly pros & cons to both sides of the equation, but as shown above one certainly doesn't need to feed live or frozen food to grow out a MONSTER fish.

 

[cchhcc]

RD, they already make "Gigantic Monster Fish Food"...... It's called "MassiveSoy!" ; )

 

[gazelle]

ok so uhh i read on my massivore delite bag that each pellet is equilivant to 2 and a half goldfish (i think i could be totally off idk) does that mean that I am cutting the life span of my fish shorter???? please respond!! what would be a good alternative because this is a big part of there diet and i would like to wean them off of it as quickly as possible if it is bad

 

[szymon328]

Having said that IMO a LOT of people in this hobby become too fixated on just growing BIGGER, and FASTER, and seldom consider longevity.



well said



back to the nutrition facts stated by oddball, i find it interesting how much more fat is in farm raised salmon than wild salmon, but its still a good thing because it decreases our impact on the oceans resources

 

[Luc53]

I'm lucky in that I have access to a local dam to supply live feeders for my natives.

Some are very fond of live food and it's hard to get them to accept prepared or even freshly dead ones.

For my Saratoga, if I don't have any live food, whole srimps or smelt is a good alternative but I make them appear live by threading one on a piece of nylon & then dangling it in the tank.

My Australian Bass are quite happy to eat either live, freshly dead or prepared food.

I found one advantage with live feeders is that when I'm away, it's easier/safer to tell my stand in to give x number of live feders every few days than getting them to use prepared food. Very little danger of left over food rotting & spoiling the water.

Luc

 

[manlyfish]

umm i have a fresh water lionfish or toadfish and i give em a live goldfish everyday how many diseases can a freshwater fish get from goldfish i know oscars can get hole in the head

 

[Szar]

Simple solution, don't use gold fish as feeders. Grow out your feeders or breed your own.

I stuff mine with the best foods, and when they are all plumpy they are fed to my fish. Wolf loves them, pikes go nuts over them.