Welcome to our forum betta_nitrite.
The advice from your LFS has placed you squarely into a fish-in cycle situation. Relax. This is your first cycle but is far from our first one. Don't hesitate to almost empty your tank and refill it with dechlorinated temperature matched water. Even a 70% water change is tiny compared to what a betta breeder would do daily. In order to raise large numbers of male bettas, they are kept in quart jars. To keep them alive and let them grow, their water is changed completely daily. That keeps the ammonia levels acceptable and the fish thrive and grow. There is no way a breeder can afford to filter each jar, so water changes are used to keep everything working just right while the males mature. You should not have to do a 100% water change, but draining your biorb down to about 1cm deep then adding back water will not harm the betta. Pristine water conditions are all that is needed for your betta's fins to heal rather quickly.
A Betta splendens can be kept with lots of other tiny tank occupants. Try choosing which one based on the nature of your tap water. If it is fairly hard, look at the small livebearers like endlers. If it is fairly soft, again look to small peaceful fish like neon tetras. In either case, wait until you have a fully cycled filter before adding anything.
The advice from your LFS has placed you squarely into a fish-in cycle situation. Relax. This is your first cycle but is far from our first one. Don't hesitate to almost empty your tank and refill it with dechlorinated temperature matched water. Even a 70% water change is tiny compared to what a betta breeder would do daily. In order to raise large numbers of male bettas, they are kept in quart jars. To keep them alive and let them grow, their water is changed completely daily. That keeps the ammonia levels acceptable and the fish thrive and grow. There is no way a breeder can afford to filter each jar, so water changes are used to keep everything working just right while the males mature. You should not have to do a 100% water change, but draining your biorb down to about 1cm deep then adding back water will not harm the betta. Pristine water conditions are all that is needed for your betta's fins to heal rather quickly.
A Betta splendens can be kept with lots of other tiny tank occupants. Try choosing which one based on the nature of your tap water. If it is fairly hard, look at the small livebearers like endlers. If it is fairly soft, again look to small peaceful fish like neon tetras. In either case, wait until you have a fully cycled filter before adding anything.
