Overstocked?

[Cichlid Junkie]

I have a 7 gallon bowfront tank with 3 cacatuoides (1m/2f) and would like to add 3 dwarf corydoras and 3 rummy nose tetras. Would that be too many fish for the tank? I have a penguin 125 to handle the bio load. What do you think? Thanks.

 

[blueblue]

It's probably okay if you conduct a frequent
parital change of water regularly, say ~20% once a week.

 

[cdawson]

The size of the filter really doesn't matter when a tank is overcrowded, which yours is, the filter doesn't export nitrates it only circulates the water to make sure the bio filter is healthy and able to eat up nitrites and ammonia.

Min. tank size for 1m/2f cactuoides is a 20 gallon long. Not for water quality issues, but for aggression issues. When your cockatoos spawn (which they will) the spawning female will be aggressive to the other female and will not let up until she's gone or dead. Away from the brood nonetheless. As for the 7g, it's overstocked adding any more fish will only make things worse.

Is the tank planted? if it's not then it's even worse, because there is no nutrient export.

Blueblue: 20% a week is not enough for a tank with good stocking levels, let alone an overstocked / undersized tank. 50% change a week is actually what everyone should do, it's not harmful to the fish or the bio filter as long as the temperature stays the same, or doesn't drastically change, as with the ph. For that tank you'd need at least a 50% a week and maybe even several smaller changes throughout the week. You'd also need to monitor your water quality constantly. Smaller tanks = more maintenance and more problems, not the opposite.

 

[blueblue]

cdawson is certainly right that a bigger tank is better (it's a golden rule in keeping aquarium fish).

BTW, what i propose here is based on the scenarios in hong kong and japan, where people keep fish in small tanks owing to space constraints . Anyhow, the way we do is to
have a sponge filter, together with other mechanical filters, to help. We never over-feed and the fish can breed well even in small tanks. We always prefer small amount and frequent water changes to big water changes for water-stability reason. As a remark, in the small tank scenario, once the female fish has laid eggs, we have to remove the male fish and other fish to prevent big fights. (You can see why many Asian friends would post messages asking whether they need to take away the male fish or not when the female fish has laid eggs, because the tank is so small that there's no hiding place for the male fish...).
That's the case here in Hong Kong and Japan, and so it's NOT impossible to keep the mentioned amount of fish in a 7 gallon tank as mentioned by Chicklid Junkie...

 

[Cichlid Junkie]

It's a small tank that will used for a fry tank once I move into a new house. Right now it omly has the 3 cacatuoides in there. I will be putting some java moss and a tall plant. I change out 20% of water (RO) weekly. I'm glad I held off on buying more fish!

 

[cdawson]

I would do more than 20%, fish give off growth inhibiting pheromones in small enironments like that and will end up stunting the growth of your fish and you don't want that!

Also, you're better off buying a bare 10 gallon for growing out fry with an air pump powered sponge filter instead of the 7 gallon.

 

[Cichlid Junkie]

cdawson,
What type of plants do you suggest?

 

[cdawson]

Anachris, rotala indica, java moss, windelov fern, wysteria, duckweed (although some have a pure hatred for this plant), fairy moss, salvinia.

Anything fast growing or that can provide excellent fry cover, as well as shelter for bullied adults.