Is This 20 Gallon High Tank Overstocked?

[Honem]

Hello all, I think my 20 gallon high tank is overstocked but I'm not sure. I have no experience with tanks this big or having this many fish in one tank, so I wanted to get a lot of opinions. I have 9 neon tetras, 7 Ember tetras, and 5 chili rasboras. I do 15% water changes a week, sometimes just top offs because I don't have a lid. Logically, based on bioload and size, I think this is just at the right amount? I know it's too many schools, but I made a mistake a few month ago and couldn't go back. If this is not too terribly overstocked, could I add just one more fish as a centerpiece? Something that doesn't need a school/is top dwelling?

The tank has a LOT of driftwood, and I'm going to be growing out all of the tall bushy plants I have, so there is definitely a lot of hiding spaces. My water parameters never change, ammonia and nitrates never stray too high. I'm welcome to any input/opinions

 

[EnlightenedOne]

Overstocking and understocking is a preference for people to know what a "good" limit is on fish bioload and amount of water changes. They're like rough guidelines to follow but if that's not your vision you can go over or under. That being said you can counter overstocking with lots of plants and your tank will adjust and produce a lot of nitrates which plants will take in if there is enough. The cycle is Ammonia-Nitrite-Nitrate so all the waste will eventually be Nitrate and the plants use all them but ultimately Nitrates are the least harmful. So kudos on achieving that balance.

BUT there is a drawback to you what you are doing. For example if your power goes out or you've got multiple filters then you are missing a big portion of your biological and maybe chemical filtration depending on your setup and since your tank is overstocked it will get fouled much quicker than say, This goes with oxygen levels in the tank, remember your plants only make oxygen when there is light. Lights out and no water agitation makes gas exchange harder so it may get stuffy in there with CO2 in an extended power outtage situation. Also your pH will steadily drop as CO2 increases turning itself into carbonic acid on top of the decrease in overall oxygen. Someone understocked or at stock would feel these affects less and take longer.

Also have to consider fish diseases should they ever present. You would have all of them get sick if one is sick or stress from being overcrowded but again that may not be the case with you. And adding a center piece is up to you but again that adds more bioload which currently your filtration and BB seem to be able to handle at present.

I'm not trying to scare you. But those are possible WCS for someone who is overstocked. I've got a few slightly overstocked as well. Not as much as yours though. You're brave hahah! But careful not to toe that line between being rash and brave. Arm yourself with knowledge.

If I were you, I'd get another 10 if you didn't want anything big and move one of the schools or a 20. Or you could stay where you are at. But I don't think I'd add anything unless I can be assured that I can handle a situation where stocking is going cause problems. Also depends on how big that centerpiece is and how much waste it will generate.

 

[PeterFishKeepin]

IMO, your very close to overstock but not overstock. I wouldnt add a 'centrepiece' fish, I would keep going waterchanges but 15% wc isnt enough try doing something like 25-50% waterchanges each week or do 50-65% waterchanges every 2 weeks. This is what i do with my 20 gal high slightly overstocked tank.

 

[Noroomforshoe]

Enlightenedone gave great advice. I still want to say what I think,
You have a lot of fish, yes they are very small almost nano, but things can get overwhelming fast. What are the results of tests for ammonia, nitrite, and nitrate? how long has this tank been running like this? Do you have trouble with nitrate climbing over 40 ppm between water changes? Are the fish getting along? or chasing each other often?

 

[Honem]

Overstocking and understocking is a preference for people to know what a "good" limit is on fish bioload and amount of water changes. They're like rough guidelines to follow but if that's not your vision you can go over or under. That being said you can counter overstocking with lots of plants and your tank will adjust and produce a lot of nitrates which plants will take in if there is enough. The cycle is Ammonia-Nitrite-Nitrate so all the waste will eventually be Nitrate and the plants use all them but ultimately Nitrates are the least harmful. So kudos on achieving that balance.

BUT there is a drawback to you what you are doing. For example if your power goes out or you've got multiple filters then you are missing a big portion of your biological and maybe chemical filtration depending on your setup and since your tank is overstocked it will get fouled much quicker than say, This goes with oxygen levels in the tank, remember your plants only make oxygen when there is light. Lights out and no water agitation makes gas exchange harder so it may get stuffy in there with CO2 in an extended power outtage situation. Also your pH will steadily drop as CO2 increases turning itself into carbonic acid on top of the decrease in overall oxygen. Someone understocked or at stock would feel these affects less and take longer.

Also have to consider fish diseases should they ever present. You would have all of them get sick if one is sick or stress from being overcrowded but again that may not be the case with you. And adding a center piece is up to you but again that adds more bioload which currently your filtration and BB seem to be able to handle at present.

I'm not trying to scare you. But those are possible WCS for someone who is overstocked. I've got a few slightly overstocked as well. Not as much as yours though. You're brave hahah! But careful not to toe that line between being rash and brave. Arm yourself with knowledge.

If I were you, I'd get another 10 if you didn't want anything big and move one of the schools or a 20. Or you could stay where you are at. But I don't think I'd add anything unless I can be assured that I can handle a situation where stocking is going cause problems. Also depends on how big that centerpiece is and how much waste it will generate.

Thank you for such detailed input! It's very useful. I've never seen the dangers of overstocking brought up when thinking specifically about power outages/equipment failure, so I will take that into consideration and think about back-up plans.

Enlightenedone gave great advice. I still want to say what I think,
You have a lot of fish, yes they are very small almost nano, but things can get overwhelming fast. What are the results of tests for ammonia, nitrite, and nitrate? how long has this tank been running like this? Do you have trouble with nitrate climbing over 40 ppm between water changes? Are the fish getting along? or chasing each other often?

My ammonia levels are always <0.25ppm, no nitrite but I think I'm starting to get some nitrates. I've had trouble with that for years, this is actually the only time I've seen the tests show virtually anything. The 20 gallon has been up for maybe a month or two, because I put it together from my other two established tanks (same substrate and driftwood). I actually just got the fish today in addition to the few others that were already there from my other tanks. Neons were fighting at first but I think they're just establishing pecking order or something like that- happened with my first ones. No one's chasing or fighting now, though. I'll wait a few weeks and see behaviors before adding anything else if I decide to