Overstocking a Planted Tank

[Alejandro Rodriguez]

Can I overstock a Planted tank?
I have a 20 gallon densely planted with hornwort. Its a species tank I only have zebra danios, is it okay to put over 20 in a 20 gallon?? (currently I have 18)

I constantly check my parameters, I have 0 ammonia, 0 nitrites and 5 ppm nitrates (hornwort is growing like Crazy)

Since my parameters are fine can its okay to overstock? I dont want to stress out the fish, maybe they dont like being that crowded

Ps.: I just want another 7

 

[Waterstrider]

I wouldn’t with danios, but for a different reason then I suspect you’re asking. Your filtration is probably great, but danios love space. They’re super active and really need room for active swimming.

 

[CryptFan]

I agree, stick with 18. 15 an Under would be better, but you already have 18. it is sole because of how active they are though.

 

[PheonixKingZ]

If you just have plants in there, I’d go with 12-15 ZD. Depending on what you can afford.

 

[Alejandro Rodriguez]

I agree, stick with 18. 15 an Under would be better, but you already have 18. it is sole because of how active they are though.

I read a time ago that some schooling fish dont school in species tank, because there's no predator fish... That turned out to be true, in the past I had danios in community tanks and they were always schooling near the top, now that I have a species tank they swim all over the place and only school when I scare them... They never are together.

The fish tank doesnt seems overstocked, I think 25 is pushing it but i dont think it will harm the fish in any way

 

[PheonixKingZ]

No, 25 is definitely to much for a 20g tank. If you want more, get a 29g.

 

[Retired Viking]

I agree with @Waterstrider, Hornwort is great at improving your water quality but they really do need plenty of room to swim. If you do decide to push the limit then do not go over 20 for the health of your fish. I have hornwort floating in my 55 gallon tetra tank, it is also great for fry to hide in.

 

[Byron]

Welcome to TFF, Alejandro.

There are a couple of significant issues mentioned in this thread, and some quite inaccurate advice being given. First off, a 20g is not sufficient tank space for Zebra Danios (Brachydanio rerio). This is a very active species, requiring at minimum a 90 cm (36 inch) length tank. A 20g is not sufficient space. More data here:

Brachydanio rerio – Zebra ‘Danio’ (Brachydanio frankei, Danio rerio) — Seriously Fish

www.seriouslyfish.com

Second, dealing with "overcrowding." No tank can be overcrowded without the fish suffering. Water quality is one aspect, and physical space is another. Different aquarists probably have different interpretations for "overcrowding." Each aquarium has a biological system, and it will support "x" fish. By "support" we mean the fish will have sufficient space to carry out their inherent natural behaviours, and the water quality will support these. Once the number of fish exceeds what the system can support biologically, the fish begin to suffer. They will be under stress, and this weakens the immune system, and it goes beyond that. The internal physiological processes of the fish are negatively affected, and this can worsen the longer it continues. The fish are slowly being killed, though this may take months, even years, and the fish will not live close to their natural expected lifespan. But by then most aquarists would not even realize what has happened.

Live plants certainly help with water quality, but they cannot possibly have any improving function when the tank is "overstocked" to begin with, as it is a downhill spiral no matter the plants. I recall reading that a 50 gallon aquarium heavily planted could support six fish the size of black neon tetras, without external assistance, but no more. The aquarium must be of a size sufficient for the species, regardless of plants.

If you already have 18 B. rerio in a 20g tank, and you have no ability to acquire a larger tank, please do not get more of them. The ones already in this tank will have enough to deal with.