So, do most of the naturally prettiest fish come from murky, or shaded waters???

[Magnum Man]

Just a morning caffeine observation… generated by the new Angel fish threads… but really from observing my South American tetras… just wondering if the brighter colors, assuming, mostly for attracting mates, and not to call predators, are likely more intense, from fish that come from conditions, that make them harder to see ( black water, or highly shaded areas ) just for example, I’ve heard that a lot of Tetras require darkness, for their eggs to hatch, and I’m looking at my newer jumbo Cardinal tetras, and thinking along the evolutionary lines, as to how they became that colorful… along the same train of thought, peacock bass likely thrive In shaded or darker waters… but then looking at my Denison Barbs, I think they come from clear sunny waters, so maybe this is just caffeine babble… looking at my ( very pretty, in brighter light ) blue lace angel, and even most of my highly colored tetras, all look much plainer in my highly shaded tank, than they would in a highly lit tank…
Any relation??? thoughts???

 

[Magnum Man]

I added “naturally” to the title, as some would argue that the prettiest fish are man made, while others would argue, that we screwed them up…

 

[Back in the fold]

I read somewhere once that the males of Nothobranchius species Killifish are so very colorful so that the females can identify them in the murky waters of their natural habitat . I can’t remember the reasoning behind that statement but think about this - a very colorful fish will stand out to a predator unless his surroundings mask him . Dark waters and foliage can hide a Neon Tetra where a Zebra Danio could swim freely anywhere with his silvery non colors . Just a thought . I’m just spit balling here .

 

[Colin_T]

A lot of brightly coloured freshwater fish do come from blackwater (contains lots of tannins and is stained tea or coffee coloured) but not all brightly coloured fish do and not all fish living in blackwater are brightly coloured.

Neon and cardinal tetras have the iridescent blue and red lines and are found in blackwater. The colour helps the fish see each other. A number of Australian and New Guinea rainbowfish are found in blackwater and some have bright colours but some don't. However, the males do show a bright coloured dorsal blaze (coloured stripe running from the start of the first dorsal fin to the tip of the nose) when breeding and this presumably evolved from living in tannin stained water. Galaxias also show a dorsal blaze when breeding and many of these fishes come from blackwater. Melanotaenia rubrostriata is found in clear water and blackwater. The fish found in blackwater have brighter red lines compared to those found in clear water.

Pygmy perch from the south-west of Western Australia are normally found in blackwater and the fish are brown and not brightly coloured except when breeding. Then the males get a red chest. Some females get iridescent green dots.

If you go to saltwater, then a lot of fish from coral reefs are brightly coloured even though they are in clear water and under very bright light. The colours on a lot of marine fish aren't just what we can see, but they also have colours that show up under uv light. Marine fish from shallow water can see more colours than us and see colours reflected from uv light. A lot of birds also see colours and have colours that show up under uv light.

Basically fish that come from darker water (not deep sea fishes but shallow water) usually have brighter colours so they can see and communicate with each other in the dark water.

 

[GaryE]

Tannins change colours, even for our poorly evolved eyes. A lot of fish see things we can't, so we are at a huge disadvantage trying to answer that question. Our senses are not tuned to their world.
When I bred cardinals and let the first light in, it hit a deeply tannin stained tank. The baby cardinals were easy to spot as tiny stripes, but not in the colour we get from adults. Or maybe we would if we had tannin tanks like that. I'd assume it's the same for adults in a flooded forest.
All the killies I've caught were in shaded zones of narrow streams where not a lot of sun got in. But a friend found a species gathering where sunlight got through the canopy, near where their brook met up with a larger river they couldn't survive in. He said the stream was glowing from the males.
Silver is usually good sunlight camouflage.
There are brightly coloured open water fish, but they tend to be larger.