Aquatic v terrestrial

[RD.]

I wonder if the fish that show shorter digestive tracts in captivity are "fixed" in this respect throughout their lives, with each successive captive-bred generation having progressively shorter intestines, or if individual fish experience a shortening of the gut throughout their lives. Would this extend to the possibility of the gut re-lengthening if the fish were re-introduced to a completely natural diet again?

There was a study years ago performed by a group of researchers out of Germany that proved exactly what you described in the warbler. The gastrointestinal length of a number of species of fish found in the Rift Lakes of Africa was dependant on the season, and what they ate. I mentioned this study in my sticky on bloat I think, I'll see if I can find a current link that still works.

edited to add: Diet predicts intestine length in Lake Tanganyika’s cichlid fishes https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2435.2009.01589.x

 

[RD.]

From that paper ….

Second, intestinal plasticity has been demonstrated experimentally in perch (Olsson et al. 2007), prickleback fish (German et al. 2006) and Tropheus (P. McIntyre and Y. Vadeboncoeur, unpublished data), and observations in Lake Malawi cichlids suggest shortening of the gut in mouthbrooding females that are unable to feed regularly (Reinthal 1989). More generally, plasticity in internal organs in response to environmental stimuli has been documented in many vertebrates (reviewed in Piersma & Lindstrom 1997; Starck 1999), including fasting snakes (Starck & Beese 2002), migrating birds (Karasov et al. 2004) and rodents in fluctuating environments (Naya, Bozinovic & Karasov 2008), and the physiological mechanisms underlying gastrointestinal plasticity are well understood in several taxa (Starck 2003). Thus, we believe that the observed variation in T. brichardi intestine length is a largely plastic response to differences in the nutrient content of their algal diet.


Both our broad phylogenetic survey and our intraspecific comparisons suggest that the intestine length of Tanganyikan cichlids is determined in large part by diet quality.

8; Fig. 3) compared with its own body (C : N < 6, n = 4, P. McIntyre, unpublished data). In the light of this imbalance, the inverse relationship between algivore intestine length and algal nitrogen content suggests that longer intestines aid in extracting nutrients from low‐quality foods. The overall inverse relationship between trophic position in the food web and gut length among 32 species of Tanganyikan cichlids (Fig. 2) also matches broad predictions from ecological stoichiometry. The nutrient imbalance between fishes and their food resources increases from piscivores (no imbalance) to invertivores (moderate imbalance) to algivores (extreme imbalance), and we found that cichlid intestine lengths increase in the same order.


The inverse relationship between intestine length and diet quality matches expectations from the general trade‐off between maximizing the extraction of nutrients and energy from the diet and minimizing the maintenance costs of digestive tissues. The presence of parallel patterns both among and within species highlights the functional significance of intestine length.

 

[Ruturaj]

Wow, great discussion guys. One thing I always had on my mind was about bacteria in our guts that help digestion, the strains needed for aquatic vs terrestrial material can be different and fish won't have same bacteria as us.

 

[Ruturaj]

That ingredients list can only be described the dogs doodahs. As a comparison, and a piss poor one at that, my hikari algae wafers first mention of seaweed is six ingredients down the list and then it's only "seaweed meal". Spirulina is even further down the list! It's worth noting that all the first ingredients on the hikari list can only be described as those nasty fillers highlighted in a recent thread.

I went online to look at prices for NLS algae max and a 2kg tub of 2mm pellets is nearly £90.00 (uk), plus delivery! That is some coin for fish food.

I was feeding hikari algae wafers as well, found out the same thing, just gave those away and went for algaemax. The pearling on my flowerhorn has been fabulous since then.

 

[Ruturaj]

I was feeding hikari algae wafers as well, found out the same thing, just gave those away and went for algaemax. The pearling on my flowerhorn has been fabulous since then.

Just ordered the book, excited to read it when it gets here.

 

[Ruturaj]

Just ordered the book, excited to read it when it gets here.

Meant to quote this.

Nutrient Requirements of Fish (1993) is pretty much the bible on this subject, well worth a read for anyone interested.

 

[Cardeater]

Not exactly. Kelp is much less costly compared to spirulina, so some commercial manufacturers went with kelp. Some use some of both, and some, such as the formula that I previously mentioned covered all of the nutritional basis, with a much wider mix. Below is the formula that I use to supplement "veggies" to all of the species that I keep, not just those with longer gastrointestinal systems. How much of that formula they recieve, depends on their classification.

RD,
I was wondering if you had a ratio in mind for supplementing algaemax for clown loaches (which I know you keep/have kept), and also for rainbowfish. I believe in a past thread, I saw a recommendation in a cichlid feeding thread of 25% algaemax?

Currently I've been feeding algaemax in pellets and wafers and then "normal" food (sinking carnivore wafers for loaches, ultra red/Probiotix/thera a) the next day. Been feeding. 3 days on, 4th day fast. I know it probably doesn't make a difference in the long run, but my mind likes to pretend to try to optimize.

Going algaemax every other day seem better or maybe 2 regular, one algaemax? I think clown loaches may be more towards the carnivore side and rainbows towards the veggie side?

 

[RD.]

All of my fish, including clown loaches, get algaemax a couple of times per week. If they leaned more on the herbivorous side of the equation, I would increase the frequency.

 

[Ruturaj]

I took a slightly different approach, I mixed algae max with northfin krill pro, 1:2, and feed it to peacocks. I think clown loaches would be good with similar ratio or frequency.