Originally Posted by Aqua Jon
Thank you. I agree, stocking the 10g is a challenge.
The betta does look great in the tank being that he is a bold and wonderful red contrasting against the plants, but I can keep little else with him in there. I've considered getting a 2.5 or 5g tank and relocating him. Then populating the 10g. I stumbled upon the pearl gourami fish... it looks interesting although it is relatively large. If my options are quite slim I may start incorporating RO water in attempt to drop the pH. And then stick with many shrimp and a single shoaling species.
However, if I'm buying fish at the LFS and they are healthy in those tanks, shouldn't they be able to survive in my tank since the water source is local?
Check the profile on the pearl gourami, re tank size and compatibility.
On the last question, not necessarily. Fish are programmed by nature to fairly specific water, and some are more sensitive to adjustments than others. Tank-raised fish over successive generations sometimes develop the ability to live normally in different water provided they are being bred and raised in that water for successive generations. Some species do not. So you need to determine if the fish in the store tank were bred and raised in water close to what you have; this obviously applies to tank-raised and not wild-caught fish. Wild caught need water comparable to their particular habitat, though here again some fish acclimate to somewhat different water better than others.
With respect to the fish being "healthy" in the store tank, how do we know it is? We don't. Some fish can adapt to varying degrees, others not so well. In both cases, they may seem OK but live shorter lives because of the water. Outwardly there may be no sign that something is wrong. Cardinal tetras for example frequently live a couple years in slightly basic water. But in soft acidic water they will live for more than 10 years. Obviously something is not to their liking; some scientists believe it is calcium blockage of the kidneys caused by the calcium in hard water. If this affects cardinals, I see no reason it won't similarly affect other soft water fish. Neon tetra have been tank-raised for decades; yet they still fare better in soft water.
In some of the profiles under water parameters, it gives the range as say slightly acidic to alightly basic, and then says fish will be more colourful in acidic water. There is obviously a reason for this.
The aim of most of us is to provide the best environment we can so our fish will live healthy and full lives. That's why we have ranges for hardness, pH and temperature. If we provide these, we can be more confident that the fish will likely be healthier.