Rainbows and water conditions

[GaryE]

I'm curious about our experience with rainbowfish from Australia and especially, Papua New Guinea. I've read a few recent postings about the need for harder water to keep these fish, and yet my M. boesemani and G wanamensis have been going great for over 15 years. I have had soft to quite soft (tds 55 this morning) water.
I used to breed them every second year, and sell the breeders after. I now have no market and just breed small numbers so I can enjoy them for as long as I can.

I know every species has its own natural history and natural needs, and water is different in different habitats. I see in collecting data on boesemani that their habitat has mostly been in the pH 6.2 to 6.5 range, but has (seasonally?) spiked to pH 9.0. It's a karst/limestone region, so the water could be harder and more mineral rich.

Still, the two species I have breeding here have grown well, and have resisted the TB that killed the Australian species (duboulayi) I paid an arm and a leg for years ago.

Who is keeping which rainbows in what water? Do we really see them as hardwater fish?

 

[Colin_T]

I had all sorts of rainbowfish from Australia and New Guinea and when they were kept in soft water (GH below 150ppm) I had nothing but problems with them. The exception to this was Iriatherina werneri and Rhadinocentrus ornatus, they were fine in soft acid water. But the Melanotaenia, Glossolepis and Chilatherina species had all sorts of health issues in soft water. I had some rainbows in with some African Rift Lake cichlids and they were doing fine so I upped the GH to 200ppm for some tanks and the fish did a lot better.

I know a number of rainbowfishes come from soft water and even acidic water but in aquariums they seem to do better in harder water. It doesn't have to be liquid rock but a GH around 150-250ppm seems to be ideal for them.

The second thing about rainbowfish is they need plant matter in their diet. At least half their diet should be plant based. When I originally started with rainbowfish I used to feed a lot of meat (fish & prawn), high protein fish flakes, and insect based foods. The fish had a lot of issues with that, some were TB related but others weren't. When I changed their diet and used a goldfish flake, vege flake, added Duckweed to all the tanks, and dropped frozen bloodworms, virtually all the problems disappeared.

----------------------

If you have pure Glossolepis wanamensis, you need to mass produce them because they are presumed extinct in the wild.

 

[Magnum Man]

I had several rainbow species... the ones that have done the best were Madagascar's & I have group of Boesemani's that came in pretty young, & seem to be doing fine, but haven't colored up yet... this tank gets it's water straight from the tap, which is house softened water, very alkaline... I intent to put a tap into the line before the softener, as our water is so hard, everything goes through the softener... when I put the tap in, it'll feed this tank, on the opposite side of the house from the bulk of my tanks, & my RO unit, across the house... aside from a bout of Ich, from putting a fish that came here sick, into the tank, the rainbows appear to be doing well on the softener water...
as @GaryE ... mentioned, if the water goes from soft to hard, depending on seasonal rains or??? one should expect the fish to thrive in that range... if a fish comes from an area, where the water stays the same, they are most likely to suffer from the variation... I would expect river fish to be more variable, & lake fish to get water that is more consistent... I would also suspect, & believe I've read, that some harder to breed fish, have an easier time, if the Ph is changed to match the water where they bred in nature

 

[Colin_T]

aside from a bout of Ich, from putting a fish that came here sick, into the tank, the rainbows appear to be doing well on the softener water...

That could be due to the salt (sodium ions) that are used in most ion exchange units to soften water.

as @GaryE ... mentioned, if the water goes from soft to hard, depending on seasonal rains or??? one should expect the fish to thrive in that range... if a fish comes from an area, where the water stays the same, they are most likely to suffer from the variation... I would expect river fish to be more variable, & lake fish to get water that is more consistent... I would also suspect, & believe I've read, that some harder to breed fish, have an easier time, if the Ph is changed to match the water where they bred in nature

Melanotaenia boesemani come from a lake and they have completely different water chemistry readings from virtually everyone who goes there and tests the water. It's an awful paradox.

 

[WhistlingBadger]

We have very soft but alkaline water here--a weird combo. My rainbows would get mouth infections frequently (I believe it was columnaris) until I started adding Epsom salts and later cichlid salt during water changes to bring the hardness up. After that, they never got sick again.

 

[Colin_T]

Most bacterial and protozoan infections that affect freshwater fishes are more prominent in soft water than in hard water. This may have some bearing on why my fish did better in hard water compared to soft water.