community tank question

Sorry but I’m going to refer you back to Derek’s words of wisdom.
If you have plans to keep even female Bettas and fancy Guppies then you really must consider returning the Serpae Tetras (if you bought them already, that is) after your tank cycle is complete – they are prodigious attackers of slow-moving and longer-finned fishes’ fins, not to mention the fry-eating aspect! – The really are like little Piranhas!!! (I think they would be as bad, if not worse, than the ‘most feared’ of the Piranhas if they grew to the same sort of size). Shops sell them as they are hardy and cheap – but, honestly, if you think Tiger Barbs have a bad reputation they aren’t in the same league as Serpae (in my opinion).

If you did buy them already then keep them until your cycling has completed then – very gradually – increase your stock levels (part-exchange the Serpae for the first group) over a period of a few weeks to allow your filter bacteria time to adjust to the higher load from the higher stock level each time. More fish = more waste = increased Ammonia and subsequently Nitrites.

You ask about the current being a problem for slow-moving fish like the Bettas but I think that since you will be growing plants in your tank then perhaps the addition of a few strategically-placed pieces of well-treated bogwood and maybe a small cave or two should serve to make it habitable for your proposed fish.

Good luck with your project, I note that you plan to do regular water changes and testing…keep these up and the battle is, I believe, half won.

John