The bottom line is you can't make a one line response and declare other views a myth without explanation. I disagree with removing parents from newly hatched fry, or vice versa, with Cichlids. Breeders I respect do it, and it works. My experience (and discussions with longtime breeders) suggests it will affect broodcare, and suggests that while broodcare is instinctive in Cichlids (as it is with us), parental modelling helps the instincts express themselves.
I like to breed fish for several generations, so I often see a different show. I'm closely watching three pairs of Parananochromis brevirostris who are maybe going to produce an F-3 brood, probably the first one in captivity. One of my f-1 pairs (for newcomers, the first fish I had were wild caught. The first brood of captive bred fry were F-1. Their fry would be F-2, and so on). I had a surprise as I always remove fry at a month, as Pelvicachromis and Apistogramma will often kill fry around that time as they prepare to spawn again and see them as a danger. My Paranaochromis were over-running my space, so I left a group of about 20 fry in with the parents. They have grown to 2m now, totally unchased even by the parents, who spawned again.
Would the fry eventually show this behaviour if I took them as soon as I saw them? I don't know. What I value isn't the color or the numbers. No one I can get these fish to wants them, so there's no money involved. I want behaviour above all, and I want behaviour across generations.
We'll never have scientific studies on this. There's not enough money in it, and not enough interest. Scientists need jobs and that means large scale aquaculture gets papers. Fish farms want mass production. Taking the fry works. It isn't something someone can set up a multigenerational study with controls etc, unless they are independently wealthy. If one of us did this for rams, one for Apisto njisseni and one for a Pelvicachromis species, we would only have data for 3 species among many anyway.
The second myth is easier. Fry can find food. They aren't brainless or immobile. They can be raised in larger tanks without losses. In larger tanks, breeders who also have jobs or families don't have to change water every day. Come here, and you'll see P. brevirostris Cichlid young, Nothobranchius palmqvisti killies, black neon tetras and Enteromius fasciolatus juvies all at decent sizes and in excellent health in my growout tanks, going on one to three water changes a week. The growth rates are just fine. The Nothobranchius growth rates are well researched, and are spot on target. The guy in the video had maybe 100 ugly linebred angelfish in a 40 gallon to represent all fish - slack thinking on his part.
Just because most of us aren't professional scientists does mean we can't use our brains with a bit of seriousness. It isn't a black and white world, and a lot of approaches work. When I see these videos, I get angry because they're lazy minds spreading lazy ideas, when for a few more sentences, they could be contributing to a debate. But they want to be gurus, and gurus are right, always.
I'm a great believer in modal auxiliary verbs (I taught writing). Can, may, might, could - they express uncertainty. If you have experimented with different systems, read serious studies or pooled resources with other aquarists who work differently than you do, you might be able to make a pronouncement. Based on an icestorm experience, I can say that all Apistogramma are dead when the water reaches 5c for more than 24 hours. That's based on observation and a really bad week in 1998.
A little respect for your own brain, and respect for other views goes a long way to getting you respected. The hobby has to relearn that.
