Protein and Fat - crawfish vs lobster vs crab vs shrimp


Staff member
I have been looking at the fat and protein content of craw/cray fish to see how close they compare in fat and protein to marine food. If I did the math correctly, this should be close.

100 grams Cray/Crawfish .. Lobster ....... Crab ........ Shrimp
Protein ....... 15.0 ................ 26.4 ............ 20.0 .......... 21.2
Fat ................ .5 .................. 1.3 ............. 1.8 ............. .88

Unfortunately, I don't know the optimum ratio but it would suggest that a full time diet of crayfish would lead to an animal eating more but getting less. If this is the case, I wonder how it fits into Roy and Joe-Ceph's thoughts that fewer feedings extend the octos (at least the bimac's) lives.

Aquarium Invertebrates: Nutritional Value Of Live Foods For The Coral Reef Aquarium, Part 2
By Rob Toonen, Ph.D.
discusses the differences. Here is part of the article

6) Freshwater Crustaceans
If you remember back to the start of the article, I went on a rant about using freshwater fishes to feed to your saltwater pets. Now, all the sudden you're reading a section about freshwater crustaceans in an article about feeding saltwater animals - what gives!? Well, the nutritional profile of freshwater crustaceans is actually surprisingly close to that of marine crustaceans (Tables 1 & 2).

Table 1: Total amount of various nutrients in a 100g sample of tissue from selected species of potential food fish as compiled by the US government (Dept of Agriculture) for nutritional comparisons of foods that are available to consumers.

Table 1: Total amount of various nutrients in a 100g sample of tissue from selected species of potential food fish as compiled by the US government (Dept of Agriculture) for nutritional comparisons of foods that are available to consumers. Food Fish Energy Protein Total Lipid Vit. B complex Vit. C
Freshwater fishes
Catfish 565 kj 15.55 g 7.59 g 3.5 mg 0.60 mg
Carp 531 kj 17.83 g 5.60 g 2.8 mg 1.60 mg
Anadromous / Brackish fishes
Wild Salmon 594 kj 19.84 g 6.34 g 11.0 mg 0
farmed Salmon 766 kj 19.90 g 10.85 g 10.0 mg 3.90 mg
Striped Bass 406 kj 17.73 g 2.33 g 3.3 mg 0
Marine fishes
Cod 343 kj 17.90 g 0.63 g 2.5 mg 2.90 mg
Snapper 418 kj 20.51 g 1.34 g 1.5 mg 1.60 mg
Freshwater crustaceans
Crayfish 301 kj 14.85 g 0.97 g 2.6 mg 0.50 mg
Marine crustaceans
mixed Shrimp 444 kj 20.31 g 1.73 g 3.0 mg 2.00 mg
Spiny Lobster 469 kj 20.60 g 1.51 g 4.8 mg 2.00 mg

Unlike the freshwater feeder goldfish comparison with marine fish, in which the fat content can be more than 20 times higher than the natural diet, freshwater crustaceans are actually slightly lower in both fat and Vitamin C content, as compared to marine crustaceans (Tables 1 & 2). There are other differences, too, but in this case, the deficiencies can be easily compensated for by using a commercially available HUFA supplement, because the freshwater crustaceans tends to be roughly equal, or perhaps a bit lower in saturated fat as well as essential fatty acids than the marine prey that make up the natural diet (Table 2). This major difference makes the use of freshwater crustaceans a much better option than freshwater fishes for feeding to your marine aquarium.

Table 2: Amount of saturated fat and a number of essential highly unsaturated fatty acids (HUFA) for each of the species groups listed in Table 1. Values for Saturated fats, LA (Omega-6, linoleic acid - 18:2), ALA (Omega-3, alpha- linolenic acid - 18:3), EPA (Omega-3, eicosapentaenoic acid - 20:5), and DHA (Omega-3, docosahexaenoic acid - 22:6) are again measured in grams from a 100g tissue sample as presented in Table 1, above. These fatty acids are among those typically included in HUFA enrichment products to supplement the diet of marine fishes in captivity. Small, non-zero numbers are denoted by < 0.01.

Table 2: Amount of saturated fat and a number of essential highly unsaturated fatty acids (HUFA) for each of the species groups listed in Table 1. Values for Saturated fats, LA (Omega-6, linoleic acid - 18:2), ALA (Omega-3, alpha-linolenic acid - 18:3), EPA (Omega-3, eicosapentaenoic acid - 20:5), and DHA (Omega-3, docosahexaenoic acid - 22:6) are again measured in grams from a 100g tissue sample as presented in Table 1, above. These fatty acids are among those typically included in HUFA enrichment products to supplement the diet of marine fishes in captivity. Small, non-zero numbers are denoted by < 0.01. Food Fish Saturated Fat LA (18:2) ALA (18:3) EPA (20:5) DHA (22:6)
Freshwater fishes
Catfish 1.77 0.88 0.10 0.07 0.21
Carp 1.08 0.52 0.27 0.24 0.11
Anadromous / Brackish fishes
Wild Salmon 0.98 0.17 0.30 0.32 0.29
farmed Salmon 2.18 0.59 0.09 0.62 1.29
Striped Bass 0.51 0.02 0.02 < 0.01 < 0.01
Marine fishes
Cod 0.08 0.01 < 0.01 0.08 0.13
Snapper 0.28 0.02 < 0.01 0.05 0.26
Freshwater crustaceans
Crayfish 0.16 0.08 0.03 0.12 0.03
Marine crustaceans
mixed Shrimp 0.33 0.03 0.01 0.26 0.22
Spiny Lobster 0.24 0.01 < 0.01 0.27 0.11

This is fortunate for most of us, because in most places small freshwater crustaceans are much easier to come by than their marine cousins. I'll discuss some of the most common and easily available of these below and explain the potential drawbacks to using them as a food for the inhabitants of your marine tank.


I'm not sure about how the nutrition factors in, but I know you can slow the growth by lowering the water temperature and reducing the amount of food given to slow down the animal's metabolism which is said to make them live longer. I don't know how much truth is in this about making them live longer but it does slow down their metabolism.


Haliphron Atlanticus
Those are measures of total protein and fat, they don't tell you the breakdown of the fatty acids. The reason marine crustaceans have been advised over freshwater is because of difference the fatty acid profile. Most of the feeding trials I have read were for larval or grow out diets, not end of life maintenance. I'm not really sure how those feeding ratios would correlate to what you are trying.


Staff member
zeekat found this study on raising cuttles with alternate foods. Unfortunately, only the abstract is free but it contains encouraging comments that crayfish are an acceptable FW feed:

The use of alternative diets to culture juvenile cuttlefish, Sepia officinalis: effects on growth and lipid composition A. FERREIRA1, L. MARQUEZ2, E. ALMANSA2,3, J.P. ANDRADE1, A. LORENZO4, P.M. DOMINGUES2Article first published online: 21 APR 2009

The effects of feeding three natural frozen diets, grass shrimp (Palaemonetes sp.), crayfish (Procambarus clarkii) and fish (Sardina pilchardus) and two semi-humid artificial diets (based on fish or shrimp powder) to the cuttlefish, Sepia officinalis, were analysed. Growth rate and feeding rate [FR; % body weight (BW) day−1] and food conversions (FC, %) were determined. Cuttlefish fed shrimp grew larger (3.8% BW day−1) and had the highest FC, followed by those fed crayfish, and sardine. The highest FR was obtained for cuttlefish fed crayfish (10.5% BW day−1). Although both artificial diets were accepted, none produced growth. Digestive gland-to-body weight ratio (DG/BW ratio) was calculated for animals fed each diet. A positive correlation (r = 0.94) between cuttlefish ingestion FR and DG weight was obtained. Mortality occurred mainly during the last week, and some cannibalism occurred among cuttlefish fed artificial diets. Finally, lipid composition of diets, DG and mantle of each group were analysed. Sardine diet was characterized by high levels of triacylglycerol (TG), whereas the main difference between shrimp and crayfish was the higher n-3/n-6 ratio found in shrimp. Changes in the lipid composition of DG were related to diet, but did not correlate with growth data. A strong loss of TG in the DG of artificial diets groups was notable. No differences in mantle lipid composition among the natural diets were found, but artificial diet groups showed higher contents of neutral lipids in their mantle respect to natural diets. According to results obtained, crayfish (P. clarkii) could be used as an alternative prey for rearing S. officinalis compared with shrimp. Artificial diets showed the worst effects in growth and mortality as well as the stronger influence on DG and mantle lipid composition of cuttlefish.
On the opposing side, however I also found this abstract:
Differences in the ω3 Fatty Acid Contents in Pond-Reared and Wild Fish and ShellfishP. CHANMUGAM, M. BOUDREAU, D.H. HWANGArticle first published online: 25 AUG 2006

The fatty acid composition of total lipids from edible portions of pond-reared prawn, catfish, and crayfish were compared with those of their wild counterparts. It was found that the lipids of the cultured animals had higher levels of ω6 fatty acids and lower ω3 fatty acid levels and ω3/ω6 ratios compared with their wild counterparts. The pelleted catfish diet was rich in ω6 fatty acids. It was concluded that the lipids of pond-reared fish and shellfish may not have the high levels of ω3 fatty acids found in wild seafood, and that the feasibility of increasing the ω3 fatty acid content by dietary manipulation, needs to be investigated.
Where fish have been univerally found to be inapproapriate (both FW and SW) this is the first article I have seen that suggest the pond raised (ie aquacultured or farm raised shrimp in the supermarkets) suffer a change in the fatty acid content (prior research revealed that the farm raised shrimp are saltwater shrimp hatched in saltwater but raised in inland ponds). It also counters the above article as to the appropriateness of crayfish for primary food consumption.


Blue Ring
The difference in n-3/n-6 ratio is normally due to the difference in feed used in aquaculture.
A lot of times wheat, bran rice based feed is used as this is cheap.
The different in n-3/n-6 ratio is also observed in farmed marine organisms.
eg., in farmed salmon the fatty acid profile can be influenced by controling the HUFAs present in the feed.


Colossal Squid
Staff member
Not sure of the biological difference between tiger shrimp and normal white shrimp is, but I know they are saltwater shrimp and they taste great!

This is from Wikipedia

* Pacific white shrimp (Litopenaeus vannamei, also called "whiteleg shrimp") is the main species cultivated in western countries. Native to the Pacific coast from Mexico to Peru, it grows to a size of 23 cm. L. vannamei accounts for 95% of the production in Latin America. It is easy to breed in captivity, but succumbs to the Taura disease.

* Giant tiger prawn (P. monodon, also known as "black tiger shrimp") occurs in the wild in the Indian Ocean and in the Pacific Ocean from Japan to Australia. The largest of all the cultivated shrimp, it can grow to a length of 36 cm and is farmed in Asia. Because of its susceptibility to whitespot disease and the difficulty of breeding it in captivity, it is gradually being replaced by L. vannamei since 2001.

Together, these two species account for about 80% of the whole farmed shrimp production.[15] Other species being bred are:
Kuruma shrimp in an aquaculture observation tank in Taiwan.

* Western blue shrimp (P. stylirostris) was a popular choice for shrimp farming in the western hemisphere, until the IHHN virus wiped out nearly the whole population in the late 1980s. A few stocks survived and became resistant against this virus. When it was discovered that some of these were also resistant against the Taura virus, some farms again bred P. stylirostris from 1997 on.

* Chinese white shrimp (P. chinensis, also known as the fleshy prawn) occurs along the coast of China and the western coast of Korea and is being farmed in China. It grows to a maximum length of only 18 cm, but tolerates colder water (min. 16 °C). Once a major factor on the world market, it is today used almost exclusively for the Chinese domestic market after a disease wiped out nearly all the stocks in 1993.

* Kuruma shrimp (P. japonicus) is farmed primarily in Japan and Taiwan, but also in Australia; the only market is in Japan, where live Kuruma shrimp reach prices of the order of US$100 per pound ($220/kg).

* Indian white shrimp (P. indicus) is a native of the coasts of the Indian Ocean and is widely bred in India, Iran and the Middle East and along the African shores.

* Banana shrimp (P. merguiensis) is another cultured species from the coastal waters of the Indian Ocean, from Oman to Indonesia and Australia. It can be grown at high densities.

Several other species of Penaeus play only a very minor role in shrimp farming. Some other kinds of shrimp also can be farmed, e.g. the "Akiami paste shrimp" or Metapenaeus spp. Their total production from aquaculture is of the order of only about 25,000 tonnes per year, small in comparison to that of the penaeids.


I dont know... I've read the difference in shrimp that are aquacultured versus wild caught is what they are fed. If a common white shrimp is fed corn meal it will obviously have different fatty acid profiles than that of a white shrimp that eats algae and detritus in the ocean. I seriously doubt whether it is a function of whether they are kept in salt versus fresh water.

Another example: If you go look at the fatty acid profiles(not to mention crude protein and fat contents) of the various frozen mysid shrimp that can be found on the market you will see a huge difference between brands. These are the same species and are probably kept in similar conditions(I have looked into culturing them and have found that brackish conditions offer the best conditions for breeding), so what accounts for the difference? I would bet that it is what they are fed.


Eric Lund, researcher from Universirty of Wisconsin, Madison, explains, "Briefly, saltwater fish all require a fatty acid that is common in marine fish oils called DHA (docosahexanoic acid) in their diet. They cannot make it from precursors, so it must be present in their food. Freshwater fish have a limited ability to make DHA from a particular precursor fatty acid of the omega-3 variety (linolenic acid), but they too can grow and reproduce well on a diet that includes DHA."

Taken from:

This article is about Artemia but that statement applies to all saltwater verts and inverts. I guess I'm saying that fatty acid profiles and crude protein/fat content are much more dependent on diet that whether they are fresh or salt water. At the very least you can just gut load the ghost shrimp with PE mysis or the like and get good results.


Colossal Squid
Staff member


Colossal Squid
Staff member
I don't believe that any shrimp used for food in the hobby are cultured. The different brands of mysis are wild caught, and I don't believe any of the live shrimp that we feed cephs are cultured - but they are kept in outdoor ponds. When I last looked into it the different protein profiles for the different frozen mysis were due to differences in species.
FWIW, I have raised entire generations of S. bandensis on FW ghost shrimp.


Blue Ring
Cool thread! This is something that is rather interesting to me. I know a bit about how the human body processes most of this stuff but I imagine a carnivorous invertebrate is a whole nother ball game. Carnivores don't have to produce as much of what their bodies need as omnivores. It's really easy for them to lose some enzymes here and there so long as what they eat can make the stuff for them! Cats for example need vitamin A in the form of retinol (the fat soluble form). Dogs and people can get their vitamin A from carrots(beta carotene). Cat foods have retinol and dog foods have beta carotene. About EFAs, they aren't actually the only fats our bodies require, we can just make the rest (as far as we know). I think cats aren't able to synthesize Omega-9 either.

About Fat to Protein ratio, why would this really matter? I would imagine that cephalopods, like people, have to turn it all into ATP before it's any good anyway? The individual fats and proteins would need different enzymes to digest, in some cases bacteria can help out here however. Lactose(not a fat or protein but a sugar) intolerance is the lack of lactase, an enzyme that breaks down lactose. If you don't have it, bacteria in your intestine obliges itself and well, it's not very fun. Almost all mammals quit producing lactase after youth. I for one am glad to have lactase! If you are lactose intolerant I'm sorry, not meaning to flaunt. :P Maybe you should go get some lactose free milk (it's not actually lactose free they just add lactase from what I understand).

My line of thinking is that all these things get synthesized somewhere. And though I'm not really of the opinion that natural is better, in this case I think it's safer until more information is available. I think the more steps in the predatory ladder you can replicate the better your chances. Whether you are feeding plankton to a freshwater feeder or feeding corn meal to a saltwater feeder it's probably better than a wc freshwater feeder. Another question along this line is how much variability is there in locales? Depending on local life from the immediate feeder down to the plankton, I imagine that octopuses (or other cephalopods) would be required to produce varying compounds (and they will only produce what they need to, genetic adaption works backwards a whole lot better than it works forwards).

Another thought is how much variety should the feeders be fed, can any one staple provide everything that needs to be passed on to the cephalopod? If shrimp, crab and fish produce nothing essential to the cephalopod, they are just a vessel and only carry what they eat. And a varied diet for the feeder would be much more important than that of your predator. This is probably an extreme and the more variation the safer is likely the actual case.

In regard to the "it works until it doesn't" case with tank mates and especially, cannibalism, I have often wondered if it wasn't due to some deficiency. I would imagine that as they age their body would change in demands and they may look beyond their staple food for a source when it isn't being met.

Though it is quite fascinating that some cephalopods have been raised for an entire generation on a freshwater feeder I don't think it's by any means an end-all, "this is all they need, want, desire, fantasize about".

I didn't mean to go on so much about all that but in my mind this discussion is much more to the core of giving our colorful invertebrate friends a good quality of life than roaming room. Also I think this is probably the biggest barrier of successful and prolific captive breeding.

Lastly, if you are still reading... I'm sorry.

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