Who Gives A Fish Forums

I've got some concerns about your tank, and I think you need to take a step back. That guy at the aquarium shop was probably just trying to make a sale, but I'm afraid you're overstocked.

Let's do some basic math - the inch per gallon rule is a good starting point. Your Swordtails will grow to about 3 inches, Guppies to 2 inches, and BNs to 5 inches. That's 43 inches of new fish you've added to your tank, which is way too much for a 20g tank.

Add in your existing fish - 6 harlequin rasboras, 6 fairy corydoras, and 1 guppy - and you're looking at another 26 inches. That's a total of 69 inches of adult fish in a tank that's only 20 gallons. That's more suitable for a 4-foot tank.

In the short term, keep a close eye on your water parameters. Your filter might struggle to keep up with the increased bioload, so you might see an ammonia or nitrite spike. Long-term, if your filter can keep up, you'll likely end up with high nitrates in 6-10 months as your fish grow.

You need to make a decision about how to move forward. You could take some fish back to the store, set up a second tank, or upgrade to a bigger tank. I know it's not what you want to hear, but I'm trying to help you avoid a disaster.

Don't take the fish store's word for it. I've been down that road, and trust me, it's not worth the trouble.

Planning to upgrade soon anyway, so I'll just transfer some fish to the new tank.

I just got off the phone with my uncle, who's actually an expert in aquariums, and he said I'm fine with the number of fish I have. He studied aquarium fish in university, so I'm not sure who to believe now. Either way, I'm still getting a new tank soon and I'll probably move some of the neptunes there.

Just a heads up, if the neptunes, swordtails and bristlenose decide to breed, those babies will add to the bio-load in the tank. For now, keep monitoring the water quality, do regular water changes, and clean that gravel. When you get that bigger tank or another one, you can move some of them over.

I'll rehome the guppy fry with friends or sell them, and same with the pleco babies when they arrive.

I just realized I don't have any female swordtails, so I guess I won't be breeding them anytime soon.

The tank might be fine short-term, but if the neptunes, swordtails, and bristlenose breed, the babies will increase the bio-load. For now, keep a close eye on water quality, do regular water changes, and clean the gravel. When you get the bigger tank, or another one, you can move some fish into it.