I have a 75 gallon aquarium that's been set up for about 2 years, with 2 Penguin 350 Biowheel filters that have a 700 gph rating and bio-stars and foam media. My original stocking plan was 10 Harlequin Rasboras, 9 Gold Tetras, 10 Panda Cories, and 6 Praecox Rainbows. I originally bought 4 Pandas, and over those 2 years 6 fry have been born and survived on their own, bringing me to my target number of 10 Catfish. That stocking has worked great so far, I do weekly 1/3 water changes and the levels have been great, with 0 ammonia, 0 Nitrites, and Nitrates always below 10 PPM. I have no live plants for this aquarium, and I don't want to get any.
Last October there was an illness, and now there are only 2 Dwarf Neon Rainbowfish rather than 6. My question now pertains to the Rainbowfish and the cories. I know I need to replenish my Rainbowfish school, and I am thinking of getting a larger Rainbowfish school this time around so I have more than 6 Rainbows total, but I'm not sure how many I could fit without overstocking.
What complicates all this is that the Panda Cories will continue to breed, and every now and then a fry will survive. Since the Pandas are by far my favorite fish, I'd rather not get rid of the fry that show up at intervals. If my Cory population continues to grow as it has, in another 1-2 years or so I may have 5 more Panda Cories. Will I have room for those additions, or will they cause my tank to be overstocked? In other words, would I have room for 15 Panda Cories, 10 Harlequin Rasboras, 9 Gold Tetras, and 6 Dwarf Neon Rainbowfish in a 75 gallon aquarium?
The second part of my question is, would I also have room for that many fish plus 1-3 more Rainbows, or would that be unwise? I don't want to buy more Rainbows and have a bigger Rainbow school now only to have to give up some of the future Panda Cory fry later.
Thanks for reading all of that!