Aggression and stocking advice

[Mrkcollins1]

Thanks in advance for any advice my aquarium is 50Lx24Hx18D 9wks old moderately planted water parameters are all fine,I have 25 cardinal tetra 5bronze Cory and 8 black widow tetra should I increase the BWT and by how many as they are being a little bit aggressive sometimes will also be increasing the cardinals but not sure as to how many would make a good size shoal want to keep it simple by not adding loads of different speacies,filtration is 2 eheim 2217,lighting 2 kessil 160 tuna sun.

 

[Byron]

Welcome to TFF.

Are those dimensions in inches? If yes, this is a 90g tank. You could certainly increase the cardinals; 100 or more in a 90g is an impressive sight.

You could increase the Black Widow Tetra, but keep in mind that this is naturally an aggressive species, even if mildly so, prone to fin nip each other and any sedate fish. The cories and cardinal tetra might become targets at some stage.

Increasing the size of the group can reduce aggressive tendencies. However, this doesn't always work "after the fact." Initially, a larger group might have kept this in check. But once individual fish decide to react to their environmental stress with aggression, it is rarely possible to eliminate it down the road. There are always exceptions of course, fish do not always follow the text books.

The aquascape also plays into this; the more "stuff" to break up the surface and water space, the less the fish may be aggressive--but this too does not always work.

Byron.

 

[Mrkcollins1]

Thanks for the advice think I will move the BWT to another tank and have them on there own,yes the tank is in inches will now over time increase cardinals and maybe add a school of 20 rummy nose or is there any other tetra that would look good with cardinals

 

[Byron]

Thanks for the advice think I will move the BWT to another tank and have them on there own,yes the tank is in inches will now over time increase cardinals and maybe add a school of 20 rummy nose or is there any other tetra that would look good with cardinals

Cardinals are fairly sedate, quiet fish, by which we mean not active swimmers. As an example, compare this to most danios, like the Zebra, which can be tearing around the tank constantly. So once you are starting with quiet fish, staying with similar is the way to do it, because quiet fish do not appreciate boisterous tankmates which causes stress.

You needn't worry about ammonia/nitrite issues with live plants, provided some of them are relatively fast growing. Floating plants are ideal for this, and frankly essential with the forest fish we are discussing anyhow. These fish do not appreciate overhead lighting, and with floating plants they will always be much more colourful, because they are more "relaxed."

Rummynose are good tankmates with cardinals; I had this combo (with other fish too) in my 5-foot Amazon tank for many years. The rummynose is somewhat of an active tetra, but not in the same sense as danios, so they tend to do well with many fish, even angelfish and discus. Rummynose (all three species) are probably the tightest shoaling tetras, by which I mean they are almost always together in the shoal, whether swimming the length of the tank (they do enjoy doing this) or cruising among plants and around branches. Many of the rasbora species tend to shoal tightly too.

Before suggesting other species, and there are many that would work here, we need to know your water parameters. GH (general or total hardness) especially, but KH (Alkalinity) and pH as well. The GH and KH you should be able to ascertain from your municipal water authority if you haven't already.

I would up the cories, definitely. Thee same species, or others, doesn't matter. But these fish live in groups of several hundred, and will always be less stressed the more there are; I know that applies to all shoaling fish, but particularly cories. In a 90g I would easily have at least 20, and more. I have 50 in my 70g which has the same footprint as the 90g, just not as tall.

 

[Mrkcollins1]

May stick with just Cory and cardinals will let you know water parameters what floating plants would you use this is first aquarium thanks again .

 

[Byron]

May stick with just Cory and cardinals will let you know water parameters what floating plants would you use this is first aquarium thanks again .

you're welcome.

Floating plants. My overall favourite is Water Sprite (Ceratopteris cornuta). This is a beauty, with extensive dangling root masses that fish love to browse for food, and spawn within. And once it is settled, you will have many plants; they form on the alternate fronds and can be easily removed and floated free. This is a true fern, so the "leaves" are called fronds, but they look and function as leaves. I'll attach a photo. Always buy this if you see it floating; there are three species, the other two are similar but better when grown rooted in the substrate and in my view do not make as lovely floating plants.

Another similar is Water Lettuce, Pistia stratiotes. Another is Tropical Frogbit. These three are true floating plants and each is lovely in its own way.

Some stem plants do well left floating; my favourite for this is Braziliasn Pennywort.