some tetras are more easier to acclimate to your water than others...
I could easily have a shoal of 50 cardinals and be down to 10 in a year....in a city water tap tank
I do have better success rates with tetras using RO treated water than anything else- theres no such thing as "weak" strains- theres just too many conditions the tetras probably went through before getting into your tank.
to add to this
its survival of the fittest- the best ones that's adaptable to your tank is the ones that gets to survive
I could easily have a shoal of 50 cardinals and be down to 10 in a year....in a city water tap tank
I do have better success rates with tetras using RO treated water than anything else- theres no such thing as "weak" strains- theres just too many conditions the tetras probably went through before getting into your tank.
to add to this
its survival of the fittest- the best ones that's adaptable to your tank is the ones that gets to survive