Category Archives: Uncle Davey's Natural Selection

I love nature. This section contains everything that falls within that interest area.

Why shouldn’t we eat catfish?

 

Who are “we” to say?

Firstly, that depends who “we”” are.

If “we” are vegans, it is because catfish are not vegetables.

If “we” are Jews, it is because Siluroides do not have scales, but either naked skin or bony plates. Therefore they are not kosher. Not kosher is not kosher, don’t ask me to justify it biologically. If you want to be frum, eat kosher, that’s all.

If “we” are anyone else, then the question turns on what do we mean by “catfish”.

The huge biodiversity of catfishes

There are over 3000 species of catfish in the world and they demonstrate vast diversity. From the candirù of South America which swims up people’s urethra if they urinate in the water, all the way up to giant Pangasias or Siluris species among the largest freshwater fishes of the world. Plus various marine species also.

“My name is Vandellia / They call me Candiru / It won’t be you be eating me / It’s me be eating you.”

Just to be clear about how astonishing that fact is, it means that 1 in 20 of the vertebrate species in the world is a species of catfish, in Siluriformes. There’s no other order of vertebrates like that. And the cladists have been trying to break it down until they were looking like clado-masochists, and the geneticists have been getting frenetic and still the Siluriformes is reckoned to be all the product of a single putative common ancestor.

Some species of catfish deliver toxins, some electric shocks, some like Corydoras or Otocinclus are too tiny to be of use as food, but are very popular in aquaria. Some species makes sounds, some get out of the water and walk about, some are transparent and you can see right through them.

There is one catfish fossil despite all of this, its name is Corydoras revelatus and the author has held it in the palm of his hand in the non-public area of the British Museum of Natural History thanks to the kindness of the late Dr Gordon Howes, ichthyologist.

Catfishes which are regularly eaten

The catfishes most commonly farmed as food are European catfish, Silurus glanis. As long as you have got one from sustainable sources they make good eating. I recommend “som fri”” in Russia or the Ukraine. Clearly they are a sports fish too, and in these cases we put them back, we don’t take them and eat them.

In the US it is channel cats, the Ictalurus and Ameiurus species which the song “Walking in Memphis”” references in the words “they got catfish on the table””. These are also fine eating as long as they are fished from sustainable and legitimate sources.

In the Amazon region they eat large Loricariids like Plecos. If you should be there as a tourist and are not a Vegan or kosher Jew, you might want to try one.

A lot of tropical rivers though are home to parasites that can transfer to people. And here I come onto the kind of catfish which has become more popular in supermarkets in recent years, namely Panga.

These can be farmed in particularly polluted parts of the Mekong river. I suggest you don’t make these a part of your menu, although trying them once might be ok.

 

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They couldn’t drag me away… (PV #36)

Original YT playout date: 26 June 2010
Duration: 12:29

The scariest thing I’ve done this year was get in the chair lift in Prague Zoo. It doesn’t stop for anyone. I wasn’t sitting very square in it and the drop was quite a long way to the wire net below.

When they saw me get on it, the lift operators started calling on the name of the second person of the Trinity and His earthly mother, which didn’t bode well.  Anyway, I filmed the whole thing. I supposed the ski lift could drag me away despite their fears that it might not hold, but the wild horses to be found at the top of it couldn’t drag me out of Prague Zoo before closing time, even though the battery was only good for the six small films you have here. I could certainly do another six at least with what’s left to show, but I’ll save that for another time.
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Are fish tanks cruel?

Are fish tanks cruel? It depends. If the fish tank is too small for the fish or the equipment in it and water changes all in combination aren’t giving the right quality of water, heat and light then that’s cruel for at least those species of fish that aren’t being catered for. Fish also have the right to hidey holes where they can enjoy their privacy for the species that need it. Of course, some individuals within a species might need it more than others. Fish differ not only between species but within a species. They even differ in their behaviour within one spawning of fry. Such is life, for organisms that reproduce sexually. It is one of the so-called “joys of sex” that Alex Comfort neglected to mention as he was more concerned with the prurient. In fact, I hope my readers haven’t even heard of him.

BB Radio – einfach der beste Mix

The mix of fish is what people tend to get wrong the most though. Putting together fish of different sizes so that the smaller ones end up getting eaten is not fair on them. Also, you should not put fin-nippers or biters like barbs or puffer fish or overly playful fish like botias in with delicate fish which don’t like to be chased around, like discus or mormyrids. Everyone should know not to mix two male Bettas, but you could have a similar result over a longer period with a lot of kinds of cichlids. When you breed fish not taking care to have males and females from separate bloodstock, this also can lead to unintentional cruelty. That is because the number of young with genetic issues and deformities is likely to be higher.

Nuh’un gemisi sizin evdedir

If you avoid those problems, there is nothing intrinsically cruel about the aquarium hobby. Our well-maintained aquarium fishes have a much better quality of life much better than that in the wild. Whole species are now being maintained in hobbyist collections which are extinct in the wild. The German hobby and Hans-Georg Evers in particular brought the Noah’s Ark capability of our hobby to peoples attention already in the 1980s.

Many livebearers and even cherry barbs are maintained despite habitat destruction in captive collections.  Other hobbyists have gone so far as to describe species to science which they have found wither coming through trade channels or in their own explorations of the Amazon.

The image shows Brachyrhamdia marthae, named by my old friend and mentor Dr. David D. Sands in honour of his then wife. David Sands used to write many articles promoting non-cruel fishkeeping, avoiding for instance keeping very large fish like red-tailed catfishes in small fish tanks where they would not thrive.

I hope some aquarists reading this will aspire to be part of some cottage conservation project, and dedicate some nice tanks to this idea.

Aqua cuna vitae, ager nobis

So, you see why it depends. Depending on what you do with your tank it can be heaven or hell for your piscine companions. In itself it is not cruel, it is a set of panes of glass.

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The Big Cat House of Prague Zoo (PV#35)

Original YT playout date: 25 June 2010
Duration: 20:36

Some big cats and some surprises too, Prague Zoo style.
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If an enemy ran up to a tank and tried to put C4s on it, what would the tank driver do?

Someone asked me to answer this as a fish tanks question.  It doesn’t look like the fish kind of tank, but if it is, then I imagine the tank owner will remove himself from the vicinity as quickly as possible on seeing the C4s, whatever they are.  If there are irreplaceable fish inside he might try to net them and carry them away in a carrier bag with water. For sure he or she will look for a replacement aquarium quickly. Obviously it’s not a situation any fishkeeper hopes for.

Supplementary question

A Quoran called Patrick Zhong then replied to the above with the question “Please inform, how do you drive a fish tank?”.

 

I replied “Very carefully, otherwise all the water slops out when you accelerate, brake, or turn corners.” Patrick then said “And how do I safely turn the fish tank in place at high rotational speeds to generate a whirlpool without killing all the fish?” My answer to this is as follows:
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Foothills of the Himalayas (PV#34)

Original YT playout date: 20 June 2010
Duration: 15:17

Prague’s Foothills of the Himalayas plus Giant Tortoises and Flying Foxes in the fourth part of the Prague Zoo series which is the thirty fourth part of my Prague Vlog series.
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It’s Never Too Late to Coypulate (PV#33)

 

Original YT playout date: 9 June 2010
Duration: 17:21

We continue this HD visit to Prague zoo, the definitive Prague Zoo experience on Youtube.
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Emerald Eyes (PV#32)

Original YT playout date: 7 June 2010
Duration: 15:01

Here we have the second part of the Prague zoo expedition. Some of this is quite pretty so I have reduced the film lengths and gone for HD coding.
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Why are there so many Polish immigrants in the UK? Why is Poland such a bad country to live in?

First of all, if Poland were a bad country to live in, I wouldn’t live here. I am, after all, British. And there are a lot of British people living here, some in cities, some in more rural locations. As well as more and more other foreigners.

The reason you see a lot of Polish people is that this country has the same population as all the countries Estonia, Latvia, Lithuania, Czech Republic, Slovakia, Hungary, Slovenia and Croatia combined. Percentagewise, more Lithuanians have emigrated than Poles, but that doesn’t mean that Lithuania is a bad country either.  However, because there are thirty Poles in the world to every Lithuanian, you’re still not going to run into them as often.

 

Polish Exploration – the example of Mikołaj Przewalski

Poles are more adventurous than most peoples. They have had more than their share of explorers and discoverers. They were not by any means always looking for an easy life, but simply highly interested in the whole world and what is in it. One example I can easily give is a wild horse species, now endangered, which lives over in Mongolia. This was discovered by a Polish guy called Przewalski and is to this day called “Przewalski’s horse”.  He also has a Przewalski’s gazelle, which is less known, and was the first to describe to science te wild Bactrian camel, although clearly that was well-known from time immemorial. What was not known, though, was that this wild Bactrian camel was a separate species to the domestic Bactrian camel. This by the way I very much doubt would stand up to genetic analysis, because people are saying that dogs are basically the same species as wolves, but apparently what domestic Bactrian camels evolved from was really a different thing entirely, so there you go.

Mikołaj Przewalski (or as he was known in Russian Николай Михайлович Пржевальский),  was born in Smolensk, a perennial favorite haunt of Poles, in the Spring of 1839, and died in a place called Karakol (yes, I know, Turkish for “police station” but this is I think an actual town in Kirgizia which bore the name Pzhevask in his honour for a while before the Turkic police stations, the black arm gang, took over, and exploration and zoology put on the back-burner) in 1888, a good ten years after the birth of Stalin, not sayin’ anything, but you have to admit the moustache has a certain familiar look…

This chap was a Russian citizen, as at that time Poland was not even on the map, and Poles were either Prussian citizens, Russian citizens or Austro-Hungarian citizens. He used his “nash chelovek” status to explore all over Central Asia wherever the Russians went. He was so adventurous, that some people even reckon that he was Stalin’s real dad, but that’s probably just an urban legend.

These days some criticism is levelled at him for being quite high-handed towards the native peoples of the places he went to, which just goes to show that it was not just the British and other West Europeans that took an Imperialist stance it was everyone, and if we had been on the receiving end instead of the dishing-out end, it is highly unlikely to have been better.

Here you can penetrate anywhere, only not with the Gospels under your arm, but with money in your pocket, a carbine in one hand and a whip in the other. Europeans must use these to come and bear away in the name of civilisation all these dregs of the human race. A thousand of our soldiers would be enough to subdue all Asia from Lake Baykal to the Himalayas….Here the exploits of Cortez can still be repeated.

(N. M. Przewalski on Asia)

 

But above all for him it was exploration, science, nature, collecting specimens of unknown plants, insects and higher life which really got him his Vega medal.

How Przewalski's gazelle appears in Sclater's "The Book of Antelopes", a seminal work on these Bovidae from 1894.

Philip Sclater, Public domain, via Wikimedia Commons The_book_of_antelopes (1894) Procapra przewalskii.

This is the same spirit that sends people to the UK. They believe that it will improve their English, which in turn will enable them to communicate on a world-wide scale and they want a nice classy English (unfortunately on building sites they tend to pick up something less than classy, but of course they don’t know that, and proceed with their h-dropping and “effing and blinding” when they get back and are trying to use English for the purposes of international tax consulting, or something equally august). They want to experience something different to their own country and culture, but which is still relatively friendly. The pay of course doesn’t hurt either, but for many it is not the prime consideration.

 

Some will stay in the UK, appreciating the education system as the grass is always greener on the other side, and wanting good UK universities and qualifications for their kids. Some are merely saving money and will use it to buy back in Poland in lush countryside a bigger mansion than any of their work colleagues in the UK will ever have.
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The Unexpected Marathon (PV#31)

Original YT playout date: 6 June 2010
Duration: 37:15

There’s me going to the zoo forgetting entirely the fact that it’s marathon time, as it was never my original intent to be in Prague at a weekend.
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Zoo tomorrow (PV#30)

Original YT playout date: 5 June 2010
Duration: 17:23

Zoos are like jam.
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Sophie’s Class visit the European Bison

20 December 2021

Original YT playout date: 29 May 2010
Duration: 49:29

This is a first ever on my channel – Sophie had a school trip to see European bison, deer, wolves, lynxes, wild boar and wild horses that there are in the Bialowiezska forest, which is the border between Poland and Belarus. It is the only place that the wisent, or European bison survives in its wild state, although some of them are in enclosures so that the public can look at them.

Sophie asked to take my old video camera with her and this is what she did, with no help from anybody. Even the postproduction I simply sat and took her instructions on the font for the titles, the colours, the choice of background music. could we have a film-maker in the making?
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