New to Cory Catfish. Does it look normal?

I'm new to cory catfish and I noticed that one of them has a pink tint to the belly and abdominal fins. I didn't notice it when we first got them a couple weeks ago. Does this look normal for them? If not, what can I do to help it? We tested the water with our API freshwater test kit and all the parameters are in the safe zones. I've seen it eating and swimming near the bottom. There are in 10 gallon with Kuhli loaches and Siamese algae eaters. Their substrate is sand and has live plants in it. The temperature is at 76F and has a filtration system and air stone. We also do 30% water changes every week. They are fed API bottom feeder pellets. It's the bigger of the two catfish in the pictures.

They look happy enough to me, what is your pH?

I can't see anything that isn't normal, the rosa tint at the belly is ok, when fish is ill you will see this sure in the anormal behavior, but 10 G for this fish and the other (especially the kuhli) is much too tiny.

The big fish (looks like a female) has a bit of pink on the lower quarter of the tail and some excess mucous on its head. This is usually caused by poor water quality.

When you say the water parameters are in the safe zone, what are the actual numbers?
The only safe level of ammonia and nitrite are 0ppm. Anything above that can cause problems. And nitrates need to be kept under 20ppm.

I would do a 75% water change and gravel clean the substrate every day for a week. Then do it once a week, or any day you have an ammonia or nitrite reading above 0ppm, or a nitrate reading above 20ppm.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

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In the 3rd and 4th pictures there are some orange balls in the plants. What are they?

I was thinking of some Botia as I told you the tank is too tiny, nevertheless I believe it's too tiny for these fish though.

Your gravel could be edgy and sharp, for corys you should pay much attention to this, yours seems to be white-colored and artificial, I would only use natural gravel and for corys better sand, in any case well rounded and not sharp.

itiwhetu said:

They look happy enough to me, what is your pH?

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pH is 7.4

Cory's will always do better in acid water.

I think the substrate (they'd like it a bit darker) , temperature and Ph are okay for these green C.aeneus.
In contrary of the often sold green Aeneus which are actually "crossbreds" with C.venezuelanus these appear the natural green type.

I also think the reddish is normal coloring and a result of wellbeing

PS Colin is right about the mucus which can be cause by all kind of irritating stuff in the water. Keep up waterchanges and if available you could add a bit of Melafix which appears to have a beneficial effect in cases like this (not a med / not to treat)

DoubleDutch said:

PS Colin is right about the mucus which can be cause by all kind of irritating stuff in the water. Keep up waterchanges and if available you could add a bit of Melafix which appears to have a beneficial effect in cases like this (not a med / not to treat)

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This is where you lower the pH and the problem disappears

itiwhetu said:

This is where you lower the pH and the problem disappears

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I highly doubt that but the use of Indian Almond or leaf litter is a good idea !

They seems fine but he does look a bit skinny so i think more food untill they fatten up.