HOUSTON (AP) _ Texas is making changes to comply with a court order for prison reforms and should not be fined $800,500 a day for failure to improve conditions, state attorneys argued Monday.

U.S. District Judge William Wayne Justice on Dec. 31 found Texas in contempt of an order to improve prison conditions and gave the state until April 1 to comply or face fines of $24 million a month. The fines were delayed pending the outcome of the hearing that began Monday and was expected to continue most of the week.

''They are not delivering the necessities of life - like clothing, plumbing, heating,'' said William Bennett Turner, attorney for the inmate plaintiffs. ''There are a number of issues.''

Attorneys for both sides said they expected Justice to issue a ruling later.

The state also has appealed the fines to the federal appeals court in New Orleans, which has not yet ruled on the matter.

James Lynaugh, the interim director of the Texas Department of Corrections, said more staff members have been hired, and that he has put pressure on the governor and Legislature to comply with the court orders.

Lynaugh said the department was recruiting additional medical staff even before the Legislature made an emergency $12.6 million appropriation to pay salaries for the new help.

In addition, the number of corrections officers, psychological and rehabilitation aides and supervisory officers exceeds court guidelines, Lynaugh said.

Turner told reporters during a break he thought the staff numbers were juggled to make the levels attractive to the judge.

''They've scurried around for 90 days in order to escape the fines,'' he said. ''They must be violating other court orders. We'll come back with contempt order after contempt order.''

During Lynaugh's cross-examination, Turner said the system's repeated violation of a 95-percent inmate capacity limit showed lack of good faith in complying with the court order.

F. Scott McCown, special assistant attorney general, said later that the prisons, which have been open to new inmates only Tuesdays and Wednesdays for much of this year, were open on a Monday for the first time in nearly three months.

''We've broken the cycle,'' he said.

The reforms Justice ordered were part of a decision in April 1981, known as the Ruiz case. Inmate David Ruiz's handwritten civil rights lawsuit in 1972 alleged poor security and living conditions and excessive crowding.